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Pollination is the transfer of
pollen Pollen is a powdery substance consisting of pollen grains which are Sporophyte, microsporophytes of spermatophyta, seed plants, which produce male gametes (sperm cells). Pollen grains have a hard coat made of sporopollenin that protects the ga ...

pollen
from an anther (male part) of a plant to the stigma (female part) of a plant, later enabling
fertilisation Fertilisation or fertilization (see American and British English spelling differences#-ise.2C -ize .28-isation.2C -ization.29, spelling differences), also known as generative fertilisation, syngamy and impregnation, is the fusion of gametes ...

fertilisation
and the production of
seed A seed is an embryonic ''Embryonic'' is the twelfth studio album by experimental rock band the Flaming Lips released on October 13, 2009, on Warner Bros. Records, Warner Bros. The band's first double album, it was released to generally positi ...

seed
s, most often by an animal or by
wind Wind is the natural movement of air or other gases relative to a planet's surface. Wind occurs on a range of scales, from thunderstorm A thunderstorm, also known as an electrical storm or a lightning storm, is a storm characterized by th ...
. Pollinating agents are animals such as insects, birds, and bats; water; wind; and even plants themselves, when
self-pollination Self-pollination is a form of pollination in which pollen from the same plant arrives at the Stigma (botany), stigma of a flower (in flowering plants) or at the ovule (in gymnosperms). There are two types of self-pollination: in autogamy, pollen is ...
occurs within a closed flower. Pollination often occurs within a species. When pollination occurs between species it can produce
hybrid Hybrid may refer to: Economics and finance * Hybrid market, a system allowing stock trades to be completed either electronically or manually * Hybrid security, a type of economic instrument Technology Electrical power generation * Hybrid generato ...
offspring in nature and in
plant breeding Plant breeding is the science of changing the traits of plants Plants are predominantly photosynthetic Photosynthesis is a process used by plants and other organisms to Energy transformation, convert light energy into chemical energy ...
work. In
angiosperm Flowering plants include multiple members of the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek#REDIRECT Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ...

angiosperm
s, after the pollen grain (
gametophyte A gametophyte () is one of the two alternating multicellular phases in the life cycles of plant Plants are predominantly photosynthetic eukaryotes of the Kingdom (biology), kingdom Plantae. Historically, the plant kingdom encompassed all ...
) has landed on the
stigma Stigma or plural stigmata, stigmas may refer to: * Social stigma, the disapproval of a person based on physical or behavioral characteristics that distinguish them from others Symbolism * Stigmata, bodily marks or wounds resembling the crucifix ...
, it germinates and develops a
pollen tube A pollen tube is a tubular structure produced by the male gametophyte A gametophyte () is one of the two alternating multicellular phases in the life cycles of plant Plants are predominantly photosynthetic eukaryotes of the Kingdom (bio ...
which grows down the
style Style is a manner of doing or presenting things and may refer to: * Architectural style An architectural style is a set of characteristics and features that make a building or other structure notable or historically identifiable. It is a sub-cla ...

style
until it reaches an
ovary The ovary is an organ found in the female reproductive system that produces an ovum. When released, this travels down the fallopian tube into the uterus, where it may become fertilized by a sperm. There is an ovary () found on each side of the b ...

ovary
. Its two
gamete A gamete ( /ˈɡæmiːt/; from Ancient Greek Ancient Greek includes the forms of the Greek language Greek ( el, label=Modern Greek Modern Greek (, , or , ''Kiní Neoellinikí Glóssa''), generally referred to by speakers simply ...
s travel down the tube to where the gametophyte(s) containing the female gametes are held within the
carpel Gynoecium (; ) is most commonly used as a collective term for the parts of a flower A flower, sometimes known as a bloom or blossom, is the reproduction, reproductive structure found in flowering plants (plants of the division Magnoliophyta, ...
. After entering an ovum cell through the
micropyleMicropyle may refer to: * Micropyle (botany) a minute opening in the integument of an ovule of a seed plant. * Micropyle (zoology), a differentiated area of surface in an egg, through which a sperm enters {{Disambiguation ...
, one male nucleus fuses with the polar bodies to produce the
endosperm 350px, right The endosperm is a tissue produced inside the seed A seed is an embryonic ''Embryonic'' is the twelfth studio album by experimental rock band the Flaming Lips released on October 13, 2009, on Warner Bros. Records, Warner Bros. The ...
tissues, while the other fuses with the
ovule In seed plant The spermatophytes, also known as phanerogams (taxon Phanerogamae) or phaenogams (taxon Phaenogamae), comprise those plants that produce seeds, hence the alternative name seed plants. They are a subset of the embryophytes or l ...

ovule
to produce the
embryo An embryo is the early stage of development of a multicellular organism A multicellular organism is an organism that consists of more than one cell (biology), cell, in contrast to a unicellular organism. All species of animals, Embryophyte, la ...

embryo
. Hence the term: "
double fertilization Double fertilization is a complex fertilization Fertilisation or fertilization (see spelling differences), also known as generative fertilisation, syngamy and impregnation, is the fusion of gametes to give rise to a new individual orga ...
". This process would result in the production of a seed made of both nutritious tissues and embryo. In
gymnosperm The gymnosperms ( lit. revealed seeds) are a group of seed-producing plants that includes conifers Conifers are a group of cone-bearing seed plants, a subset of gymnosperms. Scientifically, they make up the division Pinophyta (), also ...
s, the ovule is not contained in a carpel, but exposed on the surface of a dedicated support organ, such as the scale of a cone, so that the penetration of carpel tissue is unnecessary. Details of the process vary according to the
division Division or divider may refer to: Mathematics *Division (mathematics), the inverse of multiplication *Division algorithm, a method for computing the result of mathematical division Military *Division (military), a formation typically consisting o ...
of gymnosperms in question. Two main modes of fertilization are found in gymnosperms. Cycads and ''
Ginkgo ''Ginkgo'' is a genus Genus /ˈdʒiː.nəs/ (plural genera /ˈdʒen.ər.ə/) is a taxonomic rank In biological classification In biology, taxonomy () is the scientific study of naming, defining (Circumscription (taxonomy), circums ...

Ginkgo
'' have motile sperm that swim directly to the egg inside the ovule, whereas conifers and
gnetophyte Gnetophyta () is a division of plants, grouped within the gymnosperm The gymnosperms, also known as Acrogymnospermae, are a group of seed-producing plants that includes conifers, cycads, '' Ginkgo'', and gnetophytes. The term "gymnosperm ...
s have sperm that are unable to swim but are conveyed to the egg along a pollen tube. The study of pollination spans many disciplines, such as
botany Botany, also called , plant biology or phytology, is the science of plant life and a branch of biology. A botanist, plant scientist or phytologist is a scientist who specialises in this field. The term "botany" comes from the Ancient Greek wo ...

botany
,
horticulture Horticulture is the art of cultivating plants in gardens to produce food and medicinal ingredients, or for comfort and ornamental purposes. Horticulturists are agriculturists who grow flowers, fruits and nuts, vegetables and herbs, as well as or ...
,
entomology upright=1.2, A Phyllium sp., mimicking a leaf Entomology () is the scientific Science () is a systematic enterprise that Scientific method, builds and organizes knowledge in the form of Testability, testable explanations and predictions abo ...
, and
ecology Ecology (from el, οἶκος, "house" and el, -λογία, label=none, "study of") is the study of the relationships between living organisms, including humans, and their physical environment. Ecology considers organisms In biol ...
. The pollination process as an interaction between flower and
pollen vector
pollen vector
was first addressed in the 18th century by
Christian Konrad Sprengel Christian Konrad Sprengel (22 September 1750 – 7 April 1816) was a German naturalist Natural history is a domain of inquiry involving organisms, including animals, fungus, fungi, and plants, in their natural environment, leaning more ...
. It is important in horticulture and
agriculture Agriculture is the science, art and practice of cultivating plants and livestock. Agriculture was the key development in the rise of sedentary Image:Family watching television 1958.jpg, Exercise trends, Increases in sedentary behaviors su ...

agriculture
, because
fruit In botany Botany, also called , plant biology or phytology, is the science of plant life and a branch of biology. A botanist, plant scientist or phytologist is a scientist who specialises in this field. The term "botany" comes from the ...

fruit
ing is dependent on fertilization: the result of pollination. The study of pollination by insects is known as ''
anthecology 250px, A European honey bee collects nectar, while pollen collects on its body. Anthecology, or pollination biology, is the study of pollination as well as the relationships between flowers and their pollinators. Floral biology is a bigger field t ...
''. There are also studies in
economics Economics () is a social science Social science is the branch A branch ( or , ) or tree branch (sometimes referred to in botany Botany, also called , plant biology or phytology, is the science of plant life and a bran ...

economics
that look at the positive and negative benefits of pollination, focused on bees, and how the process affects the pollinators themselves.


Process of pollination

Pollen
germination seedlings, three days after germination Germination is the process by which an organism In biology, an organism () is any organic, life, living system that functions as an individual entity. All organisms are composed of cells (cell t ...

germination
has three stages; hydration, activation and pollen tube emergence. The pollen grain is severely dehydrated so that its mass is reduced, enabling it to be more easily transported from flower to flower. Germination only takes place after rehydration, ensuring that premature germination does not take place in the anther. Hydration allows the plasma membrane of the pollen grain to reform into its normal bilayer organization providing an effective osmotic membrane. Activation involves the development of
actin Actin is a protein family, family of Globular protein, globular multi-functional proteins that form microfilaments. It is found in essentially all Eukaryote, eukaryotic cells, where it may be present at a concentration of over 100 Micromolar, μ ...
filaments throughout the cytoplasm of the cell, which eventually become concentrated at the point from which the pollen tube will emerge. Hydration and activation continue as the pollen tube begins to grow. In conifers, the reproductive structures are borne on cones. The cones are either pollen cones (male) or ovulate cones (female), but some species are
monoecious Monoecy (; adjective form: monoecious ) is a sexual system in seed plants The spermatophytes (; ), also known as phanerogams (taxon Phanerogamae) or phaenogams (taxon Phaenogamae), comprise those plant Plants are predominantly photosynthet ...
and others
dioecious Dioecy (; Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a country located in Southeast Europe. Its population is approximately 10.7 million as o ...
. A pollen cone contains hundreds of microsporangia carried on (or borne on) reproductive structures called sporophylls. Spore mother cells in the microsporangia divide by
meiosis Meiosis (; , because it is a reductional division) is a special type of of in organisms used to produce the , such as or . It involves two rounds of division that ultimately result in four cells with only one copy of each (). Additionall ...

meiosis
to form haploid microspores that develop further by two mitotic divisions into immature male gametophytes (pollen grains). The four resulting cells consist of a large tube cell that forms the
pollen tube A pollen tube is a tubular structure produced by the male gametophyte A gametophyte () is one of the two alternating multicellular phases in the life cycles of plant Plants are predominantly photosynthetic eukaryotes of the Kingdom (bio ...
, a generative cell that will produce two sperm by mitosis, and two prothallial cells that degenerate. These cells comprise a very reduced microgametophyte, that is contained within the resistant. The pollen grains are dispersed by the wind to the female, ovulate cone that is made up of many overlapping scales (sporophylls, and thus megasporophylls), each protecting two ovules, each of which consists of a megasporangium (the nucellus) wrapped in two layers of tissue, the integument and the cupule, that were derived from highly modified branches of ancestral gymnosperms. When a pollen grain lands close enough to the tip of an ovule, it is drawn in through the micropyle ( a pore in the integuments covering the tip of the ovule) often by means of a drop of liquid known as a pollination drop. The pollen enters a pollen chamber close to the nucellus, and there it may wait for a year before it germinates and forms a pollen tube that grows through the wall of the megasporangium (=nucellus) where fertilisation takes place. During this time, the megaspore mother cell divides by meiosis to form four haploid cells, three of which degenerate. The surviving one develops as a megaspore and divides repeatedly to form an immature female gametophyte (egg sac). Two or three archegonia containing an egg then develop inside the gametophyte. Meanwhile, in the spring of the second year two sperm cells are produced by mitosis of the body cell of the male gametophyte. The pollen tube elongates and pierces and grows through the megasporangium wall and delivers the sperm cells to the female gametophyte inside. Fertilisation takes place when the nucleus of one of the sperm cells enters the egg cell in the megagametophyte's archegonium. In flowering plants, the anthers of the flower produce microspores by meiosis. These undergo mitosis to form male gametophytes, each of which contains two haploid cells. Meanwhile, the ovules produce megaspores by meiosis, further division of these form the female gametophytes, which are very strongly reduced, each consisting only of a few cells, one of which is the egg. When a pollen grain adheres to the stigma of a carpel it germinates, developing a pollen tube that grows through the tissues of the style, entering the ovule through the micropyle. When the tube reaches the egg sac, two sperm cells pass through it into the female gametophyte and fertilisation takes place.


Methods

Pollination may be biotic or abiotic. Biotic pollination relies on living
pollinator A pollinator is an animal that moves pollen File:Pollen Tube.svg, Pollen Tube Diagram Pollen is a powdery substance consisting of pollen grains which are Sporophyte, microsporophytes of spermatophyta, seed plants, which produce male gametes ...

pollinator
s to move the
pollen Pollen is a powdery substance consisting of pollen grains which are Sporophyte, microsporophytes of spermatophyta, seed plants, which produce male gametes (sperm cells). Pollen grains have a hard coat made of sporopollenin that protects the ga ...

pollen
from one flower to another. Abiotic pollination relies on wind, water or even rain. About 80% of
angiosperms Flowering plants include multiple members of the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek#REDIRECT Greek Greek may refer to: Greece Anything of, from, or related to Greece Greec ...

angiosperms
rely on biotic pollination.


Abiotic

Abiotic pollination uses nonliving methods such as wind and water to move pollen from one
flower A flower, sometimes known as a bloom or blossom Image:Cerisier du Japon Prunus serrulata.jpg, Cherry blossoms in Paris in full bloom. In botany, blossoms are the flowers of stone fruit fruit tree, trees (genus ''Prunus'') and of some other plan ...

flower
to another. This allows the plant to spend energy directly on pollen rather than on attracting pollinators with flowers and
nectar Nectar is a sugar Sugar is the generic name for sweet-tasting, soluble carbohydrate is a disaccharide found in animal milk. It consists of a molecule of D-galactose and a molecule of D-glucose bonded by beta-1-4 glycosidic linkag ...

nectar
. Pollination by wind is more common amongst abiotic pollination.


By wind

Some 98% of abiotic pollination is
anemophily Anemophily or wind pollination is a form of pollination Pollination is the transfer of pollen from an anther (male part) of a plant to the stigma (female part) of a plant, later enabling fertilisation and the production of seeds, most often by ...
, pollination by wind. This probably arose from insect pollination, most likely due to changes in the environment or the availability of pollinators. The transfer of pollen is more efficient than previously thought; wind pollinated plants have developed to have specific heights, in addition to specific floral,
stamen The stamen (plural The plural (sometimes abbreviated An abbreviation (from Latin ''brevis'', meaning ''short'') is a shortened form of a word or phrase, by any method. It may consist of a group of letters, or words taken from the full ve ...
and stigma positions that promote effective pollen dispersal and transfer.


By water

Pollination by water,
hydrophily Hydrophily is a fairly uncommon form of pollination Pollination is the transfer of pollen Pollen Tube Diagram Pollen is a powdery substance consisting of pollen grains which are male microgametophytes of seed plants, which produce male ga ...
, uses water to transport pollen, sometimes as whole anthers; these can travel across the surface of the water to carry dry pollen from one flower to another. In ''
Vallisneria spiralis ''Vallisneria spiralis'', also known as straight vallisneria, tape grass, or eel grass is a common aquarium plant that prefers good light and a nutrient rich substrate. In the wild, it can be found in tropical and sub-tropical regions worldwide. ...

Vallisneria spiralis
'', an unopened male flower floats to the surface of the water, and, upon reaching the surface, opens up and the fertile anthers project forward. The female flower, also floating, has its stigma protected from the water, while its
sepal upright=1.4, Diagram showing the parts of a mature flower. In this example the perianth is separated into a calyx (sepals) and corolla (petals) A sepal ( or ) is a part of the flower A flower, sometimes known as a bloom or blossom, is the ...
s are slightly depressed into the water, allowing the male flowers to tumble in.


By rain

Rain pollination is used by a small percentage of plants. Heavy rain discourages insect pollination and damages unprotected flowers, but can itself disperse pollen of suitably adapted plants, such as ''
Ranunculus flammula ''Ranunculus flammula'', the lesser spearwort, greater creeping spearwort or banewort, is a species of perennial plant, perennial herbaceous plants in the genus ''Ranunculus'' (buttercup), growing in damp places throughout the Boreal Kingdom. It f ...
'', '''', and ''
Caltha palustris ''Caltha palustris'', known as marsh-marigold and kingcup, is a small to medium size perennial A perennial plant or simply perennial is a plant that lives more than two years. The term ('' per-'' + '' -ennial'', "through the years") is oft ...

Caltha palustris
''. In these plants, excess rain drains allowing the floating pollen to come in contact with the stigma. In some orchids ombrophily occurs, and rain water splashes cause the anther cap to be removed, allowing for the pollen to be exposed. After exposure, raindrops causes the pollen to be shot upward, when the stipe pulls them back, and then fall into the cavity of the stigma. Thus, for the orchid ''
Acampe rigida ''Acampe rigida'' is a species of orchid native to the forests of tropical southern Asia where it grows on trees and rocks at altitudes of up to . Description ''Acampe rigida'' is a robust species with an unbranched stem up to in length and ...
'', this allows the plant to self-pollinate, which is useful when biotic pollinators in the environment have decreased.


Switching methods

It is possible for a plant have varying pollination methods, including both biotic and abiotic pollination. The orchid '''' uses both rain and butterflies, depending on its environmental conditions.


Biotic

More commonly, pollination involves
pollinator A pollinator is an animal that moves pollen File:Pollen Tube.svg, Pollen Tube Diagram Pollen is a powdery substance consisting of pollen grains which are Sporophyte, microsporophytes of spermatophyta, seed plants, which produce male gametes ...

pollinator
s (also called pollen vectors): organisms that carry or move the pollen grains from the
anther The stamen (plural The plural (sometimes list of glossing abbreviations, abbreviated ), in many languages, is one of the values of the grammatical number, grammatical category of number. The plural of a noun typically denotes a quantity greate ...
of one flower to the receptive part of the carpel or pistil (stigma) of another. Between 100,000 and 200,000 species of animal act as pollinators of the world's 250,000 species of flowering plant. The majority of these pollinators are
insect Insects (from Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken in the area around Rome, known as Latium. Through the power of the Rom ...

insect
s, but about 1,500 species of birds and mammals visit flowers and may transfer pollen between them. Besides birds and bats which are the most frequent visitors, these include monkeys, lemurs, squirrels, rodents and possums.
Entomophily covered with pollen Entomophily or insect pollination is a form of pollination whereby pollen of plants, especially but not only of flowering plant The flowering plants, also known as Angiospermae (), or Magnoliophyta (), are the most diver ...
, pollination by
insect Insects (from Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken in the area around Rome, known as Latium. Through the power of the Rom ...

insect
s, often occurs on plants that have developed colored petals and a strong
scent An odor (American English American English (AmE, AE, AmEng, USEng, en-US), sometimes called United States English or U.S. English, is the set of varieties of the English language native to the United States. Currently, American English ...
to attract insects such as, bees, wasps and occasionally ants (
Hymenoptera Hymenoptera is a large order (biology), order of insects, comprising the sawfly, sawflies, wasps, bees, and ants. Over 150,000 living species of Hymenoptera have been described, in addition to over 2,000 extinct ones. Many of the species are Para ...

Hymenoptera
),
beetle Beetles are a group of insect Insects (from Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken in the area around Rome, known a ...

beetle
s (
Coleoptera Beetles are a group of insect Insects (from Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken in the area around Rome, known a ...

Coleoptera
), moths and butterflies (
Lepidoptera Lepidoptera ( ; ) is an order (biology), order of insects that includes butterfly, butterflies and moths (both are called lepidopterans). About 180,000 species of the Lepidoptera are described, in 126 Family (biology), families and 46 Taxonomic ...

Lepidoptera
), and flies (
Diptera Flies are insects of the Order (biology), order Diptera, the name being derived from the Ancient Greek, Greek δι- ''di-'' "two", and πτερόν ''pteron'' "wing". Insects of this order use only a single pair of wings to fly, the hindwings ...

Diptera
). The existence of insect pollination dates back to the
dinosaur Dinosaurs are a diverse group of reptile Reptiles, as most commonly defined, are the animals in the Class (biology), class Reptilia , a paraphyletic grouping comprising all amniotes except synapsids (mammals and their extinct relatives) a ...

dinosaur
era. In
zoophily 250px, A rufous hummingbird ('' Selasphorus rufus'') is attracted to brightly colored flowers and assists the pollination of the plant. Zoophily is a form of pollination whereby pollen is transferred by animals, usually by invertebrates but in some ...
, pollination is performed by vertebrates such as
bird Birds are a group of warm-blooded vertebrate Vertebrates () comprise all species of animal Animals (also called Metazoa) are multicellular eukaryotic organisms that form the Kingdom (biology), biological kingdom Animalia. With ...

bird
s and
bat Bats are mammal Mammals (from Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally spoken in the area around Rome, known as Latium. Through the po ...

bat
s, particularly,
hummingbird Hummingbirds are birds Birds are a group of s constituting the Aves , characterised by s, toothless beaked jaws, the of eggs, a high rate, a four-chambered , and a strong yet lightweight . Birds live worldwide and range in size fr ...

hummingbird
s,
sunbird Sunbirds and spiderhunters make up the family In human society A society is a Social group, group of individuals involved in persistent Social relation, social interaction, or a large social group sharing the same spatial or social t ...

sunbird
s, s,
honeyeater The honeyeaters are a large and diverse family (biology), family, Meliphagidae, of small to medium-sized birds. The family includes the Epthianura, Australian chats, myzomelas, friarbirds, wattlebirds, Manorina, miners and melidectes. They are mo ...
s, and
fruit bat Megabats constitute the Family (biology), family Pteropodidae of the Order (biology), order Chiroptera (bats). They are also called fruit bats, Old World fruit bats, or—especially the genus, genera ''Acerodon'' and ''Pteropus''—Pteropus, ...
s. Ornithophily or bird pollination is the pollination of flowering plants by birds.
Chiropterophily Pollination syndromes are suites of flower A flower, sometimes known as a bloom or blossom, is the reproduction, reproductive structure found in flowering plants (plants of the division Magnoliophyta, also called angiosperms). The biologica ...
or bat pollination is the pollination of flowering plants by bats. Plants adapted to use bats or moths as pollinators typically have white petals, strong
scent An odor (American English American English (AmE, AE, AmEng, USEng, en-US), sometimes called United States English or U.S. English, is the set of varieties of the English language native to the United States. Currently, American English ...
and flower at night, whereas plants that use birds as pollinators tend to produce copious nectar and have red petals. Insect pollinators such as
honey bee A honey bee (also spelled honeybee) is a eusocial Eusociality (from Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a country located in So ...

honey bee
s (''Apis'' spp.),
bumblebee A bumblebee (or bumble bee, bumble-bee, or humble-bee) is any of over 250 species in the genus ''Bombus'', part of Apidae, one of the bee families. This genus is the only Extant taxon, extant group in the tribe Bombini, though a few extinct r ...

bumblebee
s (''Bombus'' spp.), and
butterflies Butterflies are insect Insects (from Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken in the area around Rome, known as Latiu ...

butterflies
(e.g., ''Thymelicus flavus'') have been observed to engage in flower constancy, which means they are more likely to transfer pollen to other conspecific plants. This can be beneficial for the pollinators, as flower constancy prevents the loss of pollen during interspecific flights and pollinators from clogging stigmas with pollen of other flower species. It also improves the probability that the pollinator will find productive flowers easily accessible and recognisable by familiar clues. Some flowers have specialized mechanisms to trap pollinators to increase effectiveness. Other flowers will attract pollinators by odor. For example, bee species such as '' Euglossa cordata'' are attracted to orchids this way, and it has been suggested that the bees will become intoxicated during these visits to the orchid flowers, which last up to 90 minutes. However, in general, plants that rely on pollen vectors tend to be adapted to their particular type of vector, for example day-pollinated species tend to be brightly coloured, but if they are pollinated largely by birds or specialist mammals, they tend to be larger and have larger nectar rewards than species that are strictly insect-pollinated. They also tend to spread their rewards over longer periods, having long flowering seasons; their specialist pollinators would be likely to starve if the pollination season were too short. As for the types of pollinators, reptile pollinators are known, but they form a minority in most ecological situations. They are most frequent and most ecologically significant in island systems, where insect and sometimes also bird populations may be unstable and less species-rich. Adaptation to a lack of animal food and of predation pressure, might therefore favour reptiles becoming more herbivorous and more inclined to feed on pollen and nectar. Most species of lizards in the families that seem to be significant in pollination seem to carry pollen only incidentally, especially the larger species such as
Varanidae The Varanidae are a family In human society, family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of families is to maintain the ...
and
Iguanidae The Iguanidae are a family of lizards composed of iguanas and related species which includes species such as the green iguana (''Iguana iguana''), the Lesser Antillean iguana (''Iguana delicatissima'') and the marine iguana (''Amblyrhynchus cris ...
, but especially several species of the
Gekkonidae Gekkonidae (the common geckos) is the largest family of geckos, containing over 950 described species in 64 genera. Members of the Gekkonidae comprise many of the most widespread gecko species, including house geckos (''Hemidactylus''), tokay geck ...

Gekkonidae
are active pollinators, and so is at least one species of the
Lacertidae The Lacertidae are the family (biology), family of the wall lizards, true lizards, or sometimes simply lacertas, which are native to Afro-Eurasia. It is a diverse family with at least 300 species in 39 genera. They represent the dominant group of ...
, '' Podarcis lilfordi'', which pollinates various species, but in particular is the major pollinator of ''
Euphorbia dendroides ''Euphorbia dendroides'', also known as tree spurge, is a small tree or large shrub of the family Euphorbiaceae The Euphorbiaceae, the spurge family, are a large family of flowering plant The flowering plants, also known as Angiospermae (), ...

Euphorbia dendroides
'' on various Mediterranean islands. Mammals are not generally thought of as pollinators, but some rodents, bats and marsupials are significant pollinators and some even specialise in such activities. In South Africa certain species of ''
Protea ''Protea'' () is a genus Genus /ˈdʒiː.nəs/ (plural genera /ˈdʒen.ər.ə/) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses ...

Protea
'' (in particular ''Protea humiflora'', ''P. amplexicaulis'', ''P. subulifolia'', ''P. decurrens'' and ''P. cordata'') are adapted to pollination by rodents (particularly
Cape Spiny Mouse The Cape spiny mouse (''Acomys subspinosus'') is a murid rodent found in the Western Cape Province of South Africa. They have a dorsal covering of spiny hairs with dark grey-brown coloration, and a white underbelly. The Cape Spiny Mouse has large ...
, ''Acomys subspinosus'') and
elephant shrew Elephant shrews, also called jumping shrews or sengis, are small insectivorous mammal Mammals (from Latin language, Latin , 'breast') are a group of vertebrate animals constituting the class (biology), class Mammalia (), and characterized ...

elephant shrew
s (''Elephantulus'' species). The flowers are borne near the ground, are yeasty smelling, not colourful, and sunbirds reject the nectar with its high
xylose Xylose ( grc, ξύλον, , "wood") is a sugar first isolated from wood, and named for it. Xylose is classified as a of the type, which means that it contains five atoms and includes an . It is derived from , one of the main constituents o ...

xylose
content. The mice apparently can digest the xylose and they eat large quantities of the pollen. In Australia pollination by flying, gliding and earthbound mammals has been demonstrated. Examples of pollen vectors include many species of wasps, that transport pollen of many plant species, being potential or even efficient pollinators. Experimental evidence has shown invertebrates (mostly small
crustacean Crustaceans (Crustacea ) form a large, diverse arthropod taxon which includes such animals as crabs, lobsters, crayfish, Caridea, shrimp, krill, Dendrobranchiata, prawns, woodlice, barnacles, copepods, amphipoda, amphipods and mantis shrimp. The ...
s) acting as pollinators in underwater environments. It is not yet known how important invertebrate pollinators are to their ecosystems.


Mechanism

Pollination can be accomplished by cross-pollination or by
self-pollination Self-pollination is a form of pollination in which pollen from the same plant arrives at the Stigma (botany), stigma of a flower (in flowering plants) or at the ovule (in gymnosperms). There are two types of self-pollination: in autogamy, pollen is ...
: * Cross-pollination, also called ''
allogamyAllogamy or cross-fertilization is the fertilization Fertilisation or fertilization (see spelling differences), also known as generative fertilisation, syngamy and impregnation, is the fusion of gametes to give rise to a new individual orga ...
'', occurs when pollen is delivered from the stamen of one flower to the stigma of a flower on another plant of the same species. Plants adapted for cross-pollination have several mechanisms to prevent self-pollination; the reproductive organs may be arranged in such a way that self-fertilisation is unlikely, or the stamens and carpels may mature at different times. * Self-pollination occurs when pollen from one flower pollinates the same flower or other flowers of the same individual. It is thought to have evolved under conditions when pollinators were not reliable vectors for pollen transport, and is most often seen in short-lived annual species and plants that colonize new locations. Self-pollination may include ''autogamy'', where pollen is transferred to the female part of the same flower; or ''geitonogamy'', when pollen is transferred to another flower on the same plant. Plants adapted to self-fertilize often have similar stamen and carpel lengths. Plants that can pollinate themselves and produce viable offspring are called self-fertile. Plants that cannot fertilize themselves are called self-sterile, a condition which mandates cross-pollination for the production of offspring. *''
CleistogamyCleistogamy is a type of automatic self-pollination of certain plants that can propagate by using non-opening, self-pollinating flowers. Especially well known in peanut The peanut, also known as the groundnut, goober (US), pindar (US) or monke ...
'': is self-pollination that occurs before the flower opens. The pollen is released from the anther within the flower or the pollen on the anther grows a tube down the style to the ovules. It is a type of sexual breeding, in contrast to asexual systems such as apomixis. Some ''cleistogamous'' flowers never open, in contrast to ''
chasmogamous Chasmogamy, is a plant reproductive mechanism in which pollination Pollination is the transfer of pollen Pollen Tube Diagram Pollen is a powdery substance consisting of pollen grains which are male microgametophytes of seed plants, which pr ...
'' flowers that open and are then pollinated. Cleistogamous flowers are by necessity found on self-compatible or self-fertile plants. Although certain orchids and grasses are entirely cleistogamous, other plants resort to this strategy under adverse conditions. Often there may be a mixture of both cleistogamous and chasmogamous flowers, sometimes on different parts of the plant and sometimes in mixed inflorescences. The ground bean produces cleistogamous flowers below ground, and mixed cleistogamous and chasmogamous flowers above. File:Geranium incanum 9154s.jpg, ''Geranium incanum'', like most geraniums and pelargoniums, sheds its anthers, sometimes its stamens as well, as a barrier to self-pollination. This young flower is about to open its anthers, but has not yet fully developed its pistil. File:Geranium incanum 9159s.jpg, The lower two of these ''Geranium incanum'' flowers have opened their anthers, but not yet their stigmas. Note the change of colour that signals to pollinators that they are ready for visits. The uppermost flower is somewhat more mature than the others and has already shed its stamens. File:Geranium incanum 9156s.jpg, This ''Geranium incanum'' flower has shed its stamens, and deployed the tips of its pistil without accepting pollen from its own anthers. (It might of course still receive pollen from younger flowers on the same plant.) An estimated 48.7% of plant species are either
dioecious Dioecy (; Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a country located in Southeast Europe. Its population is approximately 10.7 million as o ...
or self-incompatible obligate out-crossers. It is also estimated that about 42% of flowering plants have a mixed mating system in nature. In the most common kind of mixed mating system, individual plants produce a single type of flower and fruits may contain self-pollinated, out-crossed or a mixture of progeny types. Pollination also requires consideration of
pollenizer {{Unreferenced, date=May 2009 A pollenizer (or polleniser), sometimes pollinizer (or polliniser, see spelling differences Despite the various English dialects Dialect The term dialect (from Latin , , from the Ancient Greek word , , "d ...
s, the plants that serve as the pollen source for other plants. Some plants are '' self-compatible'' (''self-fertile'') and can pollinate and fertilize themselves. Other plants have chemical or physical barriers to
self-pollination Self-pollination is a form of pollination in which pollen from the same plant arrives at the Stigma (botany), stigma of a flower (in flowering plants) or at the ovule (in gymnosperms). There are two types of self-pollination: in autogamy, pollen is ...
. In agriculture and
horticulture Horticulture is the art of cultivating plants in gardens to produce food and medicinal ingredients, or for comfort and ornamental purposes. Horticulturists are agriculturists who grow flowers, fruits and nuts, vegetables and herbs, as well as or ...
pollination management, a good pollenizer is a plant that provides compatible, viable and plentiful pollen and blooms at the same time as the plant that is to be pollinated or has pollen that can be stored and used when needed to pollinate the desired flowers. Hybridization is effective pollination between flowers of different
species In biology, a species is the basic unit of biological classification, classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individu ...

species
, or between different breeding lines or populations. see also
Heterosis Heterosis, hybrid vigor, or outbreeding enhancement is the improved or increased function of any biological quality in a hybrid Hybrid may refer to: Economics and finance * Hybrid market, a system allowing stock trades to be completed either ...

Heterosis
.
Peach The peach (''Prunus persica'') is a deciduous In the fields of horticulture Horticulture is the art of cultivating plants in gardens to produce food and medicinal ingredients, or for comfort and ornamental purposes. Horticulturists grow ...

Peach
es are considered self-fertile because a commercial crop can be produced without cross-pollination, though cross-pollination usually gives a better crop. Apples are considered self-incompatible, because a commercial crop must be cross-pollinated. Many commercial fruit tree varieties are
grafted Grafting or graftage is a horticulture, horticultural technique whereby tissue (biology), tissues of plants are joined so as to continue their growth together. The upper part of the combined plant is called the scion () while the lower part is c ...
clone Clone or Clones or Cloning or The Clone may refer to: Places * Clones, County Fermanagh * Clones, County Monaghan, a town in Ireland Biology * Clone (B-cell), a lymphocyte clone, the massive presence of which may indicate a pathological conditio ...

clone
s,
genetically Genetics is a branch of biology concerned with the study of genes, genetic variation, and heredity in organisms.Hartl D, Jones E (2005) Though heredity had been observed for millennia, Gregor Mendel, Moravia, Moravian scientist and Augustinia ...

genetically
identical. An orchard block of apples of one variety is genetically a single plant. Many growers now consider this a mistake. One means of correcting this mistake is to graft a limb of an appropriate pollenizer (generally a variety of
crabapple ''Malus'' ( or ) is a genus Genus /ˈdʒiː.nəs/ (plural genera /ˈdʒen.ər.ə/) is a taxonomic rank In biological classification In biology Biology is the natural science that studies life and living organisms, including t ...

crabapple
) every six trees or so.


Coevolution

The first fossil record for pollination is from
fern A fern (Polypodiopsida or Polypodiophyta ) is a member of a group of vascular plant Vascular plants (from Latin ''vasculum'': duct), also known as Tracheophyta (the tracheophytes , from Greek τραχεῖα ἀρτηρία ''trācheia art ...

fern
-like plants in the late
Carboniferous The Carboniferous ( ) is a geologic period The geologic time scale (GTS) is a system of chronological dating that classifies Geology, geological strata (stratigraphy) in time. It is used by geologists, paleontology, paleontologists, and other ...
period.
Gymnosperm The gymnosperms ( lit. revealed seeds) are a group of seed-producing plants that includes conifers Conifers are a group of cone-bearing seed plants, a subset of gymnosperms. Scientifically, they make up the division Pinophyta (), also ...
s show evidence for biotic pollination as early as the
Triassic The Triassic ( ) is a geologic period The geologic time scale (GTS) is a system of chronological dating that classifies Geology, geological strata (stratigraphy) in time. It is used by geologists, paleontology, paleontologists, and other earth ...

Triassic
period. Many fossilized pollen grains show characteristics similar to the biotically dispersed pollen today. Furthermore, the gut contents, wing structures, and mouthpart
morphology Morphology, from the Greek and meaning "study of shape", may refer to: Disciplines * Morphology (archaeology), study of the shapes or forms of artifacts * Morphology (astronomy), study of the shape of astronomical objects such as nebulae, galaxies ...
of fossilized
beetles Beetles are a group of insects that form the Taxonomic rank, order Coleoptera (), in the superorder Endopterygota. Their front pair of wings are hardened into wing-cases, Elytron, elytra, distinguishing them from most other insects. The Coleo ...

beetles
and
flies Flies are insects of the order Diptera, the name being derived from the Greek δι- ''di-'' "two", and πτερόν ''pteron'' "wing". Insects of this order use only a single pair of wings to fly, the hindwings having evolved into advanced ...

flies
suggest that they acted as early pollinators. The association between
beetles Beetles are a group of insects that form the Taxonomic rank, order Coleoptera (), in the superorder Endopterygota. Their front pair of wings are hardened into wing-cases, Elytron, elytra, distinguishing them from most other insects. The Coleo ...

beetles
and
angiosperm Flowering plants include multiple members of the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek#REDIRECT Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ...

angiosperm
s during the early
Cretaceous The Cretaceous ( ) is a geological period A geological period is one of the several subdivisions of geologic time enabling cross-referencing of rocks and geologic events from place to place. These periods form elements of a hierarchy of division ...

Cretaceous
period led to parallel radiations of angiosperms and insects into the late Cretaceous. The evolution of nectaries in late Cretaceous flowers signals the beginning of the mutualism between
hymenoptera Hymenoptera is a large order (biology), order of insects, comprising the sawfly, sawflies, wasps, bees, and ants. Over 150,000 living species of Hymenoptera have been described, in addition to over 2,000 extinct ones. Many of the species are Para ...

hymenoptera
ns and angiosperms.
Bee Bees are flying insects closely related to wasps and ants, known for their role in pollination and, in the case of the best-known bee species, the western honey bee, for producing honey. Bees are a monophyly, monophyletic lineage within the ...

Bee
s provide a good example of the mutualism that exists between
hymenoptera Hymenoptera is a large order (biology), order of insects, comprising the sawfly, sawflies, wasps, bees, and ants. Over 150,000 living species of Hymenoptera have been described, in addition to over 2,000 extinct ones. Many of the species are Para ...

hymenoptera
ns and angiosperms. Flowers provide bees with nectar (an energy source) and pollen (a source of protein). When bees go from flower to flower collecting pollen they are also depositing pollen grains onto the flowers, thus pollinating them. While pollen and nectar, in most cases, are the most notable reward attained from flowers, bees also visit flowers for other resources such as oil, fragrance, resin and even waxes. It has been estimated that bees originated with the origin or diversification of
angiosperms Flowering plants include multiple members of the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek#REDIRECT Greek Greek may refer to: Greece Anything of, from, or related to Greece Greec ...

angiosperms
. In addition, cases of
coevolution In biology, coevolution occurs when two or more species In biology, a species is the basic unit of biological classification, classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined ...
between bee species and flowering plants have been illustrated by specialized adaptations. For example, long legs are selected for in ''Rediviva neliana'', a bee that collects oil from ''Diascia capsularis'', which have long spur lengths that are selected for in order to deposit pollen on the oil-collecting bee, which in turn selects for even longer legs in ''R. neliana'' and again longer spur length in ''D. capsularis'' is selected for, thus, continually driving each other's evolution.


In agriculture

The most essential staple food crops on the planet, like
wheat Wheat is a grass widely cultivated for its seed, a cereal grain which is a worldwide staple food. The many species of wheat together make up the genus ''Triticum''; the most widely grown is common wheat Common wheat (''Triticum aestivum'' ...

wheat
,
maize Maize ( ; ''Zea mays'' subsp. ''mays'', from es, maíz after tnq, mahiz), also known as corn (North American North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It can also be ...

maize
,
rice Rice is the seed A seed is an embryonic ''Embryonic'' is the twelfth studio album by experimental rock band the Flaming Lips released on October 13, 2009, on Warner Bros. Records, Warner Bros. The band's first double album, it was relea ...

rice
,
soybean The soybean, soy bean, or soya bean (''Glycine max'') is a species of legume A legume () is a plant in the family Fabaceae (or Leguminosae), or the fruit or seed of such a plant. When used as a dry grain, the seed is also called a pulse. Leg ...

soybean
s and
sorghum ''Sorghum'' is a genus of about 25 species of flowering plants in the grass family ( Poaceae). Some of these species are grown as cereals for human consumption and some in pastures for animals. One species, '' Sorghum bicolor'', was originally ...

sorghum
are wind pollinated or self pollinating. When considering the top 15 crops contributing to the human diet globally in 2013, slightly over 10% of the total human diet of plant crops (211 out of 1916 kcal/person/day) is dependent upon insect pollination.
Pollination management Honey bee A honey bee (also spelled honeybee) is a eusocial flying insect within the genus ''Apis'' of the bee clade, all native to Eurasia. They are known for their construction of wiktionary:perennial, perennial Colony (biology), colonial ne ...
is a branch of agriculture that seeks to protect and enhance present pollinators and often involves the culture and addition of pollinators in
monoculture In agriculture Agriculture is the science, art and practice of cultivating plants and livestock. Agriculture was the key development in the rise of sedentism, sedentary human civilization, whereby farming of domestication, domesticated spe ...
situations, such as commercial fruit
orchard An orchard is an intentional plantation of tree In botany, a tree is a perennial plant with an elongated Plant stem, stem, or trunk (botany), trunk, supporting branches and leaves in most species. In some usages, the definition of a tree ...

orchard
s. The largest managed pollination event in the world is in
California California is a U.S. state, state in the Western United States. With over 39.3million residents across a total area of approximately , it is the List of states and territories of the United States by population, most populous and the List of ...

California
n
almond The almond (''Prunus dulcis'', syn. ''Prunus amygdalus'') is a species of tree native to Iran Iran ( fa, ایران ), also called Persia, and officially the Islamic Republic of Iran, is a country in Western Asia Western Asia, ...

almond
orchards, where nearly half (about one million
hives Hives, also known as urticaria, is a kind of with red, raised, itchy bumps. They may also burn or sting. Often the patches of rash move around. Typically they last a few days and do not leave any long-lasting skin changes. Fewer than 5% of case ...
) of the US
honey bee A honey bee (also spelled honeybee) is a eusocial Eusociality (from Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a country located in So ...

honey bee
s are trucked to the almond orchards each spring.
New York New York most commonly refers to: * New York City, the most populous city in the United States, located in the state of New York * New York (state), a state in the northeastern United States New York may also refer to: Film and television * New ...
's
apple An apple is an edible fruit produced by an apple tree (''Malus domestica''). Apple fruit tree, trees are agriculture, cultivated worldwide and are the most widely grown species in the genus ''Malus''. The tree originated in Central Asia, wher ...

apple
crop requires about 30,000 hives;
Maine Maine () is a U.S. state, state in the New England region of the United States, bordered by New Hampshire to the west; the Gulf of Maine to the southeast; and the Provinces and territories of Canada, Canadian provinces of New Brunswick and Qu ...

Maine
's
blueberry Blueberries are perennial A perennial plant or simply perennial is a plant Plants are predominantly photosynthetic eukaryotes of the Kingdom (biology), kingdom Plantae. Historically, the plant kingdom encompassed all living things ...

blueberry
crop uses about 50,000 hives each year. The US solution to the pollinator shortage, so far, has been for commercial beekeepers to become pollination contractors and to migrate. Just as the
combine harvester The modern combine harvester, or simply combine, is a versatile machine designed to efficiently harvest a variety of grain crops. The name derives from its combining four separate harvesting operations—, , gathering, and —into a single process ...

combine harvester
s follow the
wheat Wheat is a grass widely cultivated for its seed, a cereal grain which is a worldwide staple food. The many species of wheat together make up the genus ''Triticum''; the most widely grown is common wheat Common wheat (''Triticum aestivum'' ...

wheat
harvest Harvesting is the process of gathering a ripe crop from the field Field may refer to: Expanses of open ground * Field (agriculture), an area of land used for agricultural purposes * Airfield, an aerodrome that lacks the infrastructure of an ...

harvest
from
Texas Texas (, ; Spanish language, Spanish: ''Texas'', ''Tejas'') is a state in the South Central United States, South Central region of the United States. At 268,596 square miles (695,662 km2), and with more than 29.1 million residents in 2020, ...

Texas
to
Manitoba Manitoba ( ) is a Provinces and territories of Canada, province of Canada at the Centre of Canada, longitudinal centre of the country. It is Canada's Population of Canada by province and territory, fifth-most populous province, with a population o ...

Manitoba
, beekeepers follow the bloom from south to north, to provide pollination for many different crops. In America, bees are brought to commercial plantings of
cucumber Cucumber (''Cucumis sativus'') is a widely-cultivated creeping vine plant in the '' Cucurbitaceae'' gourd family that bears cucumiform fruits In botany Botany, also called , plant biology or phytology, is the science Scien ...

cucumber
s,
squash Squash may refer to: Sports * Squash (sport), the high-speed racquet sport also known as squash racquets * Squash (professional wrestling), an extremely one-sided match in professional wrestling * Squash tennis, a game similar to squash racquets ...
,
melon Image:Cantaloupe and canary melon.jpg, Canary melon and cantaloupe A melon is any of various plants of the family Cucurbitaceae with sweet, edible, and fleshy fruit. The word "melon" can refer to either the plant or specifically to the fruit. Bo ...

melon
s,
strawberries The garden strawberry (or simply strawberry; ''Fragaria × ananassa'') is a widely grown Hybrid (biology), hybrid species of the genus ''Fragaria'', collectively known as the strawberries, which are cultivated worldwide for their fruit. The f ...

strawberries
, and many other crops. Honey bees are not the only managed pollinators: a few other
species In biology, a species is the basic unit of biological classification, classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individu ...

species
of bees are also raised as pollinators. The
alfalfa leafcutter bee ''Megachile rotundata'', the alfalfa leafcutting bee, is a European bee Bees are flying insect Insects or Insecta (from Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-Euro ...
is an important pollinator for
alfalfa Alfalfa () (''Medicago sativa''), also called lucerne, is a perennial A perennial plant or simply perennial is a plant Plants are predominantly photosynthetic eukaryotes of the Kingdom (biology), kingdom Plantae. Historically, the ...

alfalfa
seed A seed is an embryonic ''Embryonic'' is the twelfth studio album by experimental rock band the Flaming Lips released on October 13, 2009, on Warner Bros. Records, Warner Bros. The band's first double album, it was released to generally positi ...

seed
in western United States and Canada.
Bumblebee A bumblebee (or bumble bee, bumble-bee, or humble-bee) is any of over 250 species in the genus ''Bombus'', part of Apidae, one of the bee families. This genus is the only Extant taxon, extant group in the tribe Bombini, though a few extinct r ...

Bumblebee
s are increasingly raised and used extensively for
greenhouse A greenhouse (also called a glasshouse, or, if with sufficient heating, a hothouse) is a structure with walls and roof made chiefly of transparent material, such as glass, in which plant Plants are predominantly photosynthetic Photo ...

greenhouse
tomato The tomato is the edible berry A berry is a small, pulpy, and often edible fruit In botany, a fruit is the seed-bearing structure in flowering plants (also known as angiosperms) formed from the ovary after flowering. Fruits are ...

tomato
es and other crops. The
ecological Ecology (from el, οἶκος, "house" and el, -λογία, label=none, "study of") is the study of the relationships between living organisms, including humans, and their physical environment. Ecology considers organisms In biology ...
and financial importance of natural pollination by insects to
agricultural Agriculture is the practice of cultivating plants and livestock. Agriculture was the key development in the rise of sedentary Image:Family watching television 1958.jpg, Exercise trends, Increases in sedentary behaviors such as watching tele ...

agricultural
crops A crop is a plant that can be grown and harvested extensively for profit or subsistence. Crops may refer either to the harvested parts or to the harvest in a more refined state. Most crops are cultivated in agriculture Agriculture is the ...

crops
, improving their quality and quantity, becomes more and more appreciated and has given rise to new financial opportunities. The vicinity of a
forest A forest is an area of land dominated by tree In botany, a tree is a perennial plant with an elongated Plant stem, stem, or trunk (botany), trunk, supporting branches and leaves in most species. In some usages, the definition of a ...

forest
or wild
grassland Grasslands are areas where the vegetation Vegetation is an assemblage of species and the they provide. It is a general term, without specific reference to particular , life forms, structure, extent, or any other specific or geographic ...

grassland
s with native pollinators near agricultural crops, such as apples, almonds or
coffee Coffee is a drink prepared from roasted s, the seeds of from certain s in the ' genus. From the coffee fruit, the seeds are separated to produce a stable, raw product: unroasted ''green coffee''. The seeds are then , a process which transfo ...

coffee
can improve their yield by about 20%. The benefits of native pollinators may result in forest owners demanding payment for their contribution in the improved crop results – a simple example of the economic value of ecological services. Farmers can also raise native crops in order to promote native bee pollinator species as shown with '''' in Delaware and '' L. leucozonium'' in southwest Virginia. The
American Institute of Biological Sciences The American Institute of Biological Sciences (AIBS) is a nonprofit A nonprofit organization (NPO), also known as a non-business entity, not-for-profit organization, or nonprofit institution, is a legal entity organized and operated for a col ...
reports that native insect pollination saves the United States
agricultural Agriculture is the practice of cultivating plants and livestock. Agriculture was the key development in the rise of sedentary Image:Family watching television 1958.jpg, Exercise trends, Increases in sedentary behaviors such as watching tele ...

agricultural
economy nearly an estimated $3.1 billion annually through natural crop production; pollination produces some $40 billion worth of products annually in the United States alone. Pollination of food crops has become an
environmental issue Environmental issues are harmful Human impact on the environment, effects of human activity on the biophysical environment. Environmental protection is a practice of protecting the natural environment on the individual, organizational or governme ...
, due to two trends. The trend to
monoculture In agriculture Agriculture is the science, art and practice of cultivating plants and livestock. Agriculture was the key development in the rise of sedentism, sedentary human civilization, whereby farming of domestication, domesticated spe ...
means that greater concentrations of pollinators are needed at bloom time than ever before, yet the area is
forage Forage is a plant material (mainly plant leaves and stems) eaten by grazing In agriculture Agriculture is the science, art and practice of cultivating plants and livestock. Agriculture was the key development in the rise of sedentism, se ...
poor or even deadly to bees for the rest of the season. The other trend is the decline of pollinator populations, due to
pesticide Pesticides are substances that are meant to control pest (organism), pests. The term pesticide includes all of the following: herbicide, insecticides (which may include insect growth regulators, termiticides, etc.) nematicide, molluscicide, pi ...
misuse and overuse, new diseases and
parasite Parasitism is a Symbiosis, close relationship between species, where one organism, the parasite, lives on or inside another organism, the Host (biology), host, causing it some harm, and is adaptation (biology), adapted structurally to this w ...
s of bees, clearcut logging, decline of beekeeping,
suburb A suburb (or suburban area or suburbia) is a commercial Commercial may refer to: * a dose of advertising conveyed through media (such as - for example - radio or television) ** Radio advertisement ** Television advertisement * (adjective ...
an development, removal of
hedge A hedge or hedgerow is a line of closely spaced shrub A shrub (often called a bush) is a small- to medium-sized perennial A perennial plant or simply perennial is a plant that lives more than two years. The term ('' per-'' + '' -enni ...
s and other
habitat Ibex in an alpine habitat In ecology Ecology (from el, οἶκος, "house" and el, -λογία, label=none, "study of") is the study of the relationships between living organisms, including humans, and their physical environment. ...
from
farm A farm (also called an agricultural Agriculture is the practice of cultivating plants and livestock. Agriculture was the key development in the rise of sedentary Image:Family watching television 1958.jpg, Exercise trends, Increases i ...

farm
s, and public concern about bees. Widespread aerial spraying for
mosquito Mosquitoes are members of a group of almost 3,600 species In biology, a species is the basic unit of biological classification, classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defin ...

mosquito
es due to West Nile fears is causing an acceleration of the loss of pollinators. In some situations, farmers or horticulturists may aim to restrict natural pollination to only permit breeding with the preferred individuals plants. This may be achieved through the use of
pollination bagsPollination bags, sometimes called crossing bags, isolation bags or exclusion bags, are containers made of various different materials for the purpose of controlling pollination Pollination is the transfer of pollen Pollen Tube Diagram Pollen ...
.


Improving pollination in areas with suboptimal bee densities

In some instances growers’ demand for beehives far exceeds the available supply. The number of managed beehives in the US has steadily declined from close to 6 million after WWII, to less than 2.5 million today. In contrast, the area dedicated to growing bee-pollinated crops has grown over 300% in the same time period. Additionally, in the past five years there has been a decline in winter managed beehives, which has reached an unprecedented rate of colony losses at near 30%. At present, there is an enormous demand for beehive rentals that cannot always be met. There is a clear need across the agricultural industry for a management tool to draw pollinators into cultivations and encourage them to preferentially visit and pollinate the flowering crop. By attracting pollinators like honey bees and increasing their foraging behavior, particularly in the center of large plots, we can increase grower returns and optimize yield from their plantings. ISCA Technologies, from Riverside California, created a semiochemical formulation called SPLAT Bloom, that modifies the behavior of honey bees, inciting them to visit flowers in every portion of the field.


Environmental impacts

Loss of pollinators, also known as
Pollinator decline Pollinator decline is the reduction in abundance of insect Insects or Insecta (from Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken ...
(of which
colony collapse disorder Colony collapse disorder (CCD) is an abnormal phenomenon that occurs when the majority of worker bees in a honey bee bee colony, colony disappear, leaving behind a queen bee, queen, plenty of food, and a few nurse bees to care for the remaining i ...
is perhaps the most well known) has been noticed in recent years. These loss of pollinators have caused a disturbance in early plant regeneration processes such as seed dispersal and pollination. Early processes of plant regeneration greatly depend on plant-animal interactions and because these interactions are interrupted, biodiversity and ecosystem functioning are threatened. Pollination by animals aids in the genetic variability and diversity within plants because it allows for out-crossing instead for self-crossing. Without this genetic diversity there would be a lack of traits for natural selection to act on for the survival of the plant species.
Seed dispersal Seed dispersal is the movement, spread or transport of seed A seed is an embryonic ''Embryonic'' is the twelfth studio album by experimental rock band the Flaming Lips released on October 13, 2009, on Warner Bros. Records, Warner Bros. The ban ...
is also important for plant fitness because it allows plants the ability to expand their populations. More than that, it permits plants to escape environments that have changed and have become difficult to reside in. All of these factors show the importance of pollinators for plants, which are a significant part of the foundation for a stable ecosystem. If only a few species of plants depended on Loss of pollinators is especially devastating because there are so many plant species rely on them. More than 87.5% of
angiosperms Flowering plants include multiple members of the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek#REDIRECT Greek Greek may refer to: Greece Anything of, from, or related to Greece Greec ...

angiosperms
, over 75% of tropical tree species, and 30-40% of tree species in temperate regions depend on pollination and seed dispersal. Factors that contribute to pollinator decline include
habitat destruction Habitat destruction (also termed habitat loss and habitat reduction) is the process by which a natural habitat Ibex in an alpine habitat In ecology, the term habitat summarises the array of resources, physical and biotic factors that are pr ...
,
pesticide Pesticides are substances that are meant to control pest (organism), pests. The term pesticide includes all of the following: herbicide, insecticides (which may include insect growth regulators, termiticides, etc.) nematicide, molluscicide, pi ...
,
parasitism Parasitism is a close relationship between species In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular biology, ...

parasitism
/
diseases A disease is a particular abnormal condition that negatively affects the structure or function of all or part of an organism, and that is not due to any immediate external injury. Diseases are often known to be medical conditions that ar ...
, and
climate change Contemporary climate change includes both the global warming caused by humans, and its impacts on Earth's weather patterns. There have been previous periods of climate change, but the current changes are more rapid than any known even ...
. The more destructive forms of human disturbances are land use changes such as fragmentation, selective logging, and the conversion to secondary forest habitat.
Defaunation Defaunation is the global, local or functional extinction Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the endling, las ...
of
frugivore A frugivore is an animal that thrives mostly on raw fruits or succulent fruit-like produce of plants such as roots, shoots, nuts and seeds. Approximately 20% of mammalian herbivores eat fruit. Frugivores are highly dependent on the abundance and ...
s is also an important driver. These alterations are especially harmful due to the sensitivity of the pollination process of plants. Research on tropical palms found that defaunation has caused a decline in seed dispersal, which causes a decrease in genetic variability in this species. Habitat destruction such as fragmentation and selective logging remove areas that are most optimal for the different types of pollinators, which removes pollinators food resources, nesting sites, and leads to isolation of populations. The effect of pesticides on pollinators has been debated because it is difficult to determine that a single pesticide is the cause as opposed to a mixture or other threats. Whether exposure alone causes damage, or if the duration and potency are also factors is unknown. However,
insecticide Insecticides are substances used to kill insects. They include ovicides and larvicides used against insect Egg (biology), eggs and larvae, respectively. Insecticides are used in agriculture, medicine, Industry (manufacturing), industry and by ...
s have negative effects, as in the case of
neonicotinoid Neonicotinoids (sometimes shortened to neonics ) are a class of neuro-active insecticide Insecticides are substances used to kill insect Insects or Insecta (from Latin Latin (, or , ) is a classical language belonging to the Italic lan ...
s that harm bee colonies. Many researchers believe it is the synergistic effects of these factors which are ultimately detrimental to pollinator populations. In the agriculture industry, climate change is causing a "pollinator crisis". This crisis is affecting the production of crops, and the relating costs, due to a decrease in pollination processes. This disturbance can be phenological or spatial. In the first case, species that normally occur in similar seasons or time cycles, now have different responses to environmental changes and therefore no longer interact. For example, a tree may flower sooner than usual, while the pollinator may reproduce later in the year and therefore the two species no longer coincide in time. Spatial disturbances occur when two species that would normally share the same distribution now respond differently to climate change and are shifting to different regions.


Examples of affected pollinators

The most known and understood pollinator, bees, have been used as the prime example of the decline in pollinators. Bees are essential in the pollination of agricultural crops and wild plants and are one of the main insects that perform this task. Out of the bees species, the honey bee or ''
Apis mellifera The western honey bee or European honey bee (''Apis mellifera'') is the most common of the 7–12 species of honey bees worldwide. The genus name ''Apis'' is Latin for "bee", and ''mellifera'' is the Latin for "honey-bearing", referring to the spe ...

Apis mellifera
'' has been studied the most and in the United States, there has been a loss of 59% of colonies from 1947 to 2005. The decrease in populations of the honey bee have been attributed to pesticides, genetically modified crops, fragmentation, parasites and diseases that have been introduced. There has been a focus on neonicotinoids effects on honey bee populations. Neonicotinoids insecticides have been used due to its low mammalian toxicity, target specificity, low application rates, and broad spectrum activity. However, the insecticides are able to make its way throughout the plant, which includes the pollen and nectar. Due to this, it has been shown to effect on the nervous system and colony relations in the honey bee populations.
Butterflies Butterflies are insect Insects (from Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken in the area around Rome, known as Latiu ...

Butterflies
too have suffered due to these modifications. Butterflies are helpful ecological indicators since they are sensitive to changes within the environment like the season, altitude, and above all,
human impact on the environment Human impact on the environment or anthropogenic impact on the environment includes changes to biophysical environments A biophysical environment is a biotic and abiotic surrounding of an organism In biology, an organism (from An ...
. Butterfly populations were higher within the natural forest and were lower in open land. The reason for the difference in density is the fact that in open land the butterflies would be exposed to desiccation and predation. These open regions are caused by habitat destruction like logging for timber, livestock grazing, and firewood collection. Due to this destruction, butterfly species' diversity can decrease and it is known that there is a correlation in butterfly diversity and plant diversity.


Food security and pollinator decline

Besides the imbalance of the ecosystem caused by the decline in pollinators, it may jeopardise
food security Food security is the measure of the availability of food and individuals' Economic inequality, ability to access it. According to the United Nations' Committee on World Food Security, food security is defined as meaning that all people, at all ti ...
. Pollination is necessary for plants to continue their populations and 3/4 of the plant species that contribute to the world's food supply are plants that require pollinators. Insect pollinators, like bees, are large contributors to crop production, over 200 billion dollars worth of crop species are pollinated by these insects. Pollinators are also essential because they improve crop quality and increase genetic diversity, which is necessary in producing fruit with nutritional value and various flavors. Crops that do not depend on animals for pollination but on the wind or self-pollination, like corn and potatoes, have doubled in production and make up a large part of the human diet but do not provide the micronutrients that are needed. The essential nutrients that are necessary in the human diet are present in plants that rely on animal pollinators. There have been issues in vitamin and mineral deficiencies and it is believed that if pollinator populations continue to decrease these deficiencies will become even more prominent.


Plant–pollinator networks

Wild pollinators often visit a large number of plant species and plants are visited by a large number of pollinator species. All these relations together form a network of interactions between plants and pollinators. Surprising similarities were found in the structure of networks consisting out of the interactions between plants and pollinators. This structure was found to be similar in very different ecosystems on different continents, consisting of entirely different species. The structure of plant-pollinator networks may have large consequences for the way in which pollinator communities respond to increasingly harsh conditions. Mathematical models, examining the consequences of this network structure for the stability of pollinator communities suggest that the specific way in which plant-pollinator networks are organized minimizes competition between pollinators and may even lead to strong indirect facilitation between pollinators when conditions are harsh. This means that pollinator species together can survive under harsh conditions. But it also means that pollinator species collapse simultaneously when conditions pass a critical point. This simultaneous collapse occurs, because pollinator species depend on each other when surviving under difficult conditions. Such a community-wide collapse, involving many pollinator species, can occur suddenly when increasingly harsh conditions pass a critical point and recovery from such a collapse might not be easy. The improvement in conditions needed for pollinators to recover, could be substantially larger than the improvement needed to return to conditions at which the pollinator community collapsed.


Economics of pollination

While there are 200,000 - 350,000 different species of animals that help pollination, bees are responsible for majority of the pollination for consumed crops, providing between $235 and $577 US billion of benefits to global food production. Since the early 1900s, beekeepers in the United States started renting out their colonies to farmers to increase the farmer's crop yields, earning additional revenue from providing privatized pollination. As of 2016, 41% of an average US beekeeper's revenue comes from providing such pollination service to farmers, making it the biggest proportion of their income, with the rest coming from sales of honey, beeswax, government subsidy, etc. This is an example of how a
positive externality In economics Economics () is the social science that studies how people interact with value; in particular, the Production (economics), production, distribution (economics), distribution, and Consumption (economics), consumption of goods ...

positive externality
, pollination of crops from beekeeping and honey-making, was successfully accounted for and incorporated into the overall market for agriculture. On top of assisting food production, pollination service provide beneficial spillovers as bees
germinate seedlings, three days after germination Germination is the process by which an organism In biology, an organism () is any organic, life, living system that functions as an individual entity. All organisms are composed of cells (cell t ...

germinate
not only the crops, but also other plants around the area that they are set loose to pollinate, increasing
biodiversity Biodiversity is the biological variety and Genetic variability, variability of life, life on Earth. Biodiversity is a measure of variation at the Genetics, genetic, species, and ecosystem level. Terrestrial biodiversity is usually greater near ...

biodiversity
for the local
ecosystem An ecosystem (or ecological system) consists of all the organisms and the physical environment with which they interact. These biotic and abiotic components are linked together through nutrient cycles and energy flows. Energy enters the syst ...

ecosystem
. There is even further spillover as biodiversity increases ecosystem resistance for wildlife and crops. Due to their role of pollination in crop production, commercial honeybees are considered to be livestock by the
US Department of Agriculture The United States Department of Agriculture (USDA), also known as the Agriculture Department, is the United States federal executive departments, federal executive department responsible for developing and executing federal laws related to farmin ...
. The impact of pollination varies by crop. For example,
almond The almond (''Prunus dulcis'', syn. ''Prunus amygdalus'') is a species of tree native to Iran Iran ( fa, ایران ), also called Persia, and officially the Islamic Republic of Iran, is a country in Western Asia Western Asia, ...

almond
production in the United States, an $11 billion industry based almost exclusively in the state of California, is heavily dependent on bees for pollination of almond trees. Almond industry uses up to 82% of the services in the pollination market. Each February, around 60% of the all bee colonies in the US are moved to California's Central Valley. Over the past decade, beekeepers across the US have reported that the mortality rate of their bee colonies has stayed constant at about 30% every year, making the deaths an expected cost of business for the beekeepers. While the exact cause of this phenomenon is unknown, according to the
US Department of Agriculture The United States Department of Agriculture (USDA), also known as the Agriculture Department, is the United States federal executive departments, federal executive department responsible for developing and executing federal laws related to farmin ...
Colony Collapse Disorder Colony collapse disorder (CCD) is an abnormal phenomenon that occurs when the majority of worker bees in a honey bee bee colony, colony disappear, leaving behind a queen bee, queen, plenty of food, and a few nurse bees to care for the remaining i ...
Progress Report it can be traced to factors such as pollution, pesticides, and pathogens from evidences found in areas of the colonies affected and the colonies themselves. Pollution and pesticides are detrimental to the health of the bees and their colonies as the bees' ability to pollinate and return to their colonies are great greatly compromised. Moreover, California's Central Valley is determined by the
World Health Organization The World Health Organization (WHO) is a specialized agency of the United Nations United Nations Specialized Agencies are autonomous organizations working with the United Nations and each other through the co-ordinating machinery of the Unit ...
as the location of country's worst
air pollution Air pollution is the presence of substances in the atmosphere that are harmful to the health of humans and other Outline of life forms, living beings, or cause damage to the climate or to materials. There are different types of air pollutants, ...

air pollution
. Almond pollinating bees, approximately 60% of the bees in the US as mentioned above, will be mixed with bees from thousands of other hives provided by different beekeepers, making them exponentially susceptible to diseases and
mites Mites are small arachnid Arachnida () is a Class (biology), class of joint-legged invertebrate animals (arthropods), in the subphylum Chelicerata. Arachnida includes orders containing spiders (the largest order), scorpions, ticks, mites, opi ...

mites
that any of them could be carrying. The deaths do not stop at commercial honeybees as there is evidence of significant pathogen spillover to other pollinators including wild bumble bees, infecting up to 35-100% of wild bees within 2 km radius of commercial pollination. The negative
externality In economics Economics () is the social science that studies how people interact with value; in particular, the Production (economics), production, distribution (economics), distribution, and Consumption (economics), consumption of goods ...

externality
of private pollination services is the decline of biodiversity through the deaths of commercial and wild bees. Despite losing about a third of their workforce every year, beekeepers continue to rent out their bees to almond farms due to the high pay from the almond industry. In 2016, a colony rented out for almond pollination gave beekeepers an income of $165 per colony rented, around three times from average of other crops that use the pollination rental service. However, a recent study published in Oxford Academic's Journal of Economic
Entomology upright=1.2, A Phyllium sp., mimicking a leaf Entomology () is the scientific Science () is a systematic enterprise that Scientific method, builds and organizes knowledge in the form of Testability, testable explanations and predictions abo ...
found that once the costs for maintaining bees specifically for almond pollination, including
overwintering Overwintering is the process by which some organism In biology, an organism () is any organic, life, living system that functions as an individual entity. All organisms are composed of cells (cell theory). Organisms are classified by tax ...
, summer management, and the replacement dying bees are considered, almond pollination is barely or not profitable for average beekeepers.


See also

* Canadian Pollination Initiative *
Cheating (biology) Cheating is a term used in behavioral ecology Behavioral ecology, also spelled behavioural ecology, is the study of the evolution Evolution is change in the Heredity, heritable Phenotypic trait, characteristics of biological populations ov ...
* Floral color change * Pollinator-mediated selection * Fruit tree pollination *
Hand-pollination Hand pollination, also known as mechanical pollination is a technique that can be used to pollinate Pollination is the transfer of pollen from a male part of a plant to a female part of a plant, later enabling fertilisation and the production of s ...
* Paul Knuth * Hermann Müller (botanist) *
Plant reproductive morphology Plant reproductive morphology is the study of the physical form and structure (the ) of those parts of plants directly or indirectly concerned with . Among all living organisms, s, which are the reproductive structures of , are the most varied p ...
* Pollen DNA barcoding * Polli:Nation


References


Notes

* * * *


Further reading

*


External links


Resources on Pollinators
from the
National Academies A national academy is an organizational body, usually operating with state financial support and approval, that co-ordinates scholarly research Research is "creativity, creative and systematic work undertaken to increase the stock of knowl ...

The Pollination Home pagePollination in Hydroponics
* {{Authority control Horticulture Plant sexuality