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''Cuscuta'' (), commonly known as dodder or amarbel, is a genus of over 201 species of yellow, orange, or red (rarely green)
parasitic plant A parasitic plant is a plant that derives some or all of its nutritional requirements from another living plant. They make up about 1% of angiosperms and are found in almost every biome. All parasitic plants develop a specialized organ called th ...
s. Formerly treated as the only genus in the family Cuscutaceae, it now is accepted as belonging in the
morning glory Morning glory (also written as morning-glory) is the common name for over 1,000 species of flowering plants in the family Convolvulaceae, whose current taxonomy and systematics are in flux. Morning glory species belong to many genera, some of ...
family,
Convolvulaceae Convolvulaceae (), commonly called the bindweeds or morning glories, is a family of about 60 genera and more than 1,650 species. These species are primarily herbaceous vines, but also include trees, shrubs and herbs. The tubers of several spe ...
, on the basis of the work of the
Angiosperm Phylogeny Group The Angiosperm Phylogeny Group (APG) is an informal international group of systematic botanists who collaborate to establish a consensus on the taxonomy of flowering plants (angiosperms) that reflects new knowledge about plant relationships disc ...
. The genus is found throughout the
temperate In geography, the temperate climates of Earth occur in the middle latitudes (23.5° to 66.5° N/S of Equator), which span between the tropics and the polar regions of Earth. These zones generally have wider temperature ranges throughout ...
and
tropical The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in the Southern Hemisphere at S. The tropics are also referred to ...
regions of the world, with the greatest species diversity in
subtropical The subtropical zones or subtropics are geographical and climate zones to the north and south of the tropics. Geographically part of the temperate zones of both hemispheres, they cover the middle latitudes from to approximately 35° north a ...
and tropical regions; the genus becomes rare in cool
temperate climate In geography, the temperate climates of Earth occur in the middle latitudes (23.5° to 66.5° N/S of Equator), which span between the tropics and the polar regions of Earth. These zones generally have wider temperature ranges throughout ...
s, with only four species native to
northern Europe The northern region of Europe has several definitions. A restrictive definition may describe Northern Europe as being roughly north of the southern coast of the Baltic Sea, which is about 54°N, or may be based on other geographical factors ...
. Folk names include: strangle tare, scaldweed, beggarweed, lady's laces, fireweed, wizard's net, devil's guts, devil's hair, devil's ringlet, goldthread, hailweed, hairweed, hellbine, love vine, pull-down, strangleweed, angel hair, and witch's hair.


Description

Cuscuta can be identified by its thin stems appearing leafless, with the
leaves A leaf ( : leaves) is any of the principal appendages of a vascular plant stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, st ...
reduced to minute scales. In these respects it closely resembles the similarly parasitic, but unrelated genus, '' Cassytha''. From mid-summer to early autumn, the vines can produce small
fruit In botany, a fruit is the seed-bearing structure in flowering plants that is formed from the ovary after flowering. Fruits are the means by which flowering plants (also known as angiosperms) disseminate their seeds. Edible fruits in partic ...
that take the same color as the vine, and are approximately the size of a common pea. It has very low levels of
chlorophyll Chlorophyll (also chlorophyl) is any of several related green pigments found in cyanobacteria and in the chloroplasts of algae and plants. Its name is derived from the Greek words , ("pale green") and , ("leaf"). Chlorophyll allow plants to ...
; some species such as '' Cuscuta reflexa'' can photosynthesize slightly, while others such as '' C. europaea'' are entirely dependent on the host plants for nutrition. Dodder
flower A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants (plants of the division Angiospermae). The biological function of a flower is to facilitate reproduction, usually by providing a mechanis ...
s range in color from white to pink to yellow to cream. Some flower in the early summer, others later, depending on the species. The
seed A seed is an embryonic plant enclosed in a protective outer covering, along with a food reserve. The formation of the seed is a part of the process of reproduction in seed plants, the spermatophytes, including the gymnosperm and angiosper ...
s are minute and produced in large quantities. They have a hard coating, and typically can survive in the soil for 5–10 years, sometimes longer. Dodder seeds sprout at or near the surface of the soil. Although dodder
germination Germination is the process by which an organism grows from a seed or spore. The term is applied to the sprouting of a seedling from a seed of an angiosperm or gymnosperm, the growth of a sporeling from a spore, such as the spores of fungi, fe ...
can occur without a host, it has to reach a green plant quickly and is adapted to grow towards the nearby plants by following chemosensory clues. If a plant is not reached within 5 to 10 days of germination, the dodder seedling will die. Before a host plant is reached, the dodder, as other plants, relies on food reserves in the embryo; the
cotyledons A cotyledon (; ; ; , gen. (), ) is a significant part of the embryo within the seed of a plant, and is defined as "the embryonic leaf in seed-bearing plants, one or more of which are the first to appear from a germinating seed." The numb ...
, though present, are
vestigial Vestigiality is the retention, during the process of evolution, of genetically determined structures or attributes that have lost some or all of the ancestral function in a given species. Assessment of the vestigiality must generally rely on co ...
.


Parasitism

After a dodder attaches itself to a plant, it wraps itself around it. If the host contains food beneficial to dodder, the dodder produces
haustoria In botany and mycology, a haustorium (plural haustoria) is a rootlike structure that grows into or around another structure to absorb water or nutrients. For example, in mistletoe or members of the broomrape family, the structure penetrates th ...
that insert themselves into the vascular system of the host. The vestigial root of the dodder in the soil then dies. The dodder can grow and attach itself to multiple plants. In tropical areas, it can grow more or less continuously and may reach high into the canopy of shrubs and trees; in cold temperate regions, it is an
annual plant An annual plant is a plant that completes its life cycle, from germination to the production of seeds, within one growing season, and then dies. The length of growing seasons and period in which they take place vary according to geographical ...
and is restricted to relatively low vegetation that can be reached by new seedlings each spring. Dodder is parasitic on a very wide variety of plants, including a number of agricultural and horticultural crop species, such as
alfalfa Alfalfa () (''Medicago sativa''), also called lucerne, is a perennial flowering plant in the legume family Fabaceae. It is cultivated as an important forage crop in many countries around the world. It is used for grazing, hay, and silage, as ...
,
lespedeza ''Lespedeza'' is a genus of some 40 species (including nothospecies) of flowering plants in the pea family (Fabaceae), commonly known as bush clovers or (particularly East Asian species) Japanese clovers (''hagi''). The genus is native to warm t ...
,
flax Flax, also known as common flax or linseed, is a flowering plant, ''Linum usitatissimum'', in the family Linaceae. It is cultivated as a food and fiber crop in regions of the world with temperate climates. Textiles made from flax are known in ...
,
clover Clover or trefoil are common names for plants of the genus ''Trifolium'' (from Latin ''tres'' 'three' + ''folium'' 'leaf'), consisting of about 300 species of flowering plants in the legume or pea family Fabaceae originating in Europe. The genus ...
,
potato The potato is a starchy food, a tuber of the plant ''Solanum tuberosum'' and is a root vegetable native to the Americas. The plant is a perennial in the nightshade family Solanaceae. Wild potato species can be found from the southern Uni ...
es,
chrysanthemum Chrysanthemums (), sometimes called mums or chrysanths, are flowering plants of the genus ''Chrysanthemum'' in the family Asteraceae. They are native to East Asia and northeastern Europe. Most species originate from East Asia and the cent ...
,
dahlia Dahlia (, ) is a genus of bushy, tuberous, herbaceous perennial plants native to Mexico and Central America. A member of the Asteraceae (former name: Compositae) family of dicotyledonous plants, its garden relatives thus include the sunflower, ...
,
helenium ''Helenium'' is a genus of annuals and herbaceous perennial plants in the family Asteraceae, native to the Americas. They bear yellow or orange daisy-like composite flowers. A number of these species (particularly ''Helenium autumnale'') have ...
,
trumpet vine ''Campsis,'' commonly known as trumpet creeper or trumpet vine, is a genus of flowering plants in the family Bignoniaceae, native to woodlands in China and North America. It consists of two species, both of which are vigorous deciduous perennial ...
,
ivy ''Hedera'', commonly called ivy (plural ivies), is a genus of 12–15 species of evergreen climbing or ground-creeping woody plants in the family Araliaceae, native to western, central and southern Europe, Macaronesia, northwestern Africa and ...
and petunias. It is an
ectoparasite Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson ha ...
and is categorized as
holoparasitic A parasitic plant is a plant that derives some or all of its nutritional requirements from another living plant. They make up about 1% of angiosperms and are found in almost every biome. All parasitic plants develop a specialized organ called th ...
plant, or a plant that is non-photosynthetic and is completely dependent on a host. Dodder ranges in severity based on its species and the species of the host, the time of attack, and whether any viruses are also present in the host plant. By debilitating the host plant, dodder decreases the ability of plants to resist viral diseases, and dodder can also spread plant diseases from one host to another if it is attached to more than one plant. This is of economic concern in agricultural systems, where an annual drop of 10% yield can be devastating. There has been an emphasis on dodder vine control in order to manage plant diseases in the field.


Host location

A report published in ''Science'' in 2006 demonstrated that dodder use airborne
volatile organic compound Volatile organic compounds (VOCs) are organic compounds that have a high vapour pressure at room temperature. High vapor pressure correlates with a low boiling point, which relates to the number of the sample's molecules in the surrounding air, a ...
cues to locate their host plants. Seedlings of '' C. pentagona'' exhibit positive growth responses to volatiles released by tomato and other species of host plants. When given a choice between volatiles released by the preferred host tomato and the non-host wheat, the parasite grew toward the former. Further experiments demonstrated attraction to a number of individual compounds released by host plants and repellence by one compound released by wheat. These results do not rule out the possibility that other cues, such as light, may also play a role in host location.


Host defenses

Less is known about host defenses against dodder and other parasitic plants than is known about plant defenses against herbivores and pathogens. In one study,
tomato The tomato is the edible berry of the plant ''Solanum lycopersicum'', commonly known as the tomato plant. The species originated in western South America, Mexico, and Central America. The Mexican Nahuatl word gave rise to the Spanish word ...
plants were found to employ complex mechanisms to defend against dodder. Two pathways, using
jasmonic acid Jasmonic acid (JA) is an organic compound found in several plants including jasmine. The molecule is a member of the jasmonate class of plant hormones. It is biosynthesized from linolenic acid by the octadecanoid pathway. It was first isolate ...
and
salicylic acid Salicylic acid is an organic compound with the formula HOC6H4CO2H. A colorless, bitter-tasting solid, it is a precursor to and a metabolite of aspirin (acetylsalicylic acid). It is a plant hormone, and has been listed by the EPA Toxic Substa ...
, were activated in response to attack by '' Cuscuta pentagona''. Dodder attack was also found to induce production of volatiles, including 2- carene,
α-pinene α-Pinene is an organic compound of the terpene class, one of two isomers of pinene. It is an alkene and it contains a reactive four-membered ring. It is found in the oils of many species of many coniferous trees, notably the pine. It is also ...
,
limonene Limonene is a colorless liquid aliphatic hydrocarbon classified as a cyclic monoterpene, and is the major component in the oil of citrus fruit peels. The -isomer, occurring more commonly in nature as the fragrance of oranges, is a flavoring a ...
, and
β-phellandrene Phellandrenes are a pair of organic compounds that have a similar molecular structure and similar chemical properties. α-Phellandrene and β-phellandrene are cyclic monoterpenes and are double-bond isomers. In α-phellandrene, both double bonds ...
. It is not known if or how these volatiles defend the host, but they could potentially interfere with the dodder's ability to locate and select hosts. Also, the presence of
trichomes Trichomes (); ) are fine outgrowths or appendages on plants, algae, lichens, and certain protists. They are of diverse structure and function. Examples are hairs, glandular hairs, scales, and papillae. A covering of any kind of hair on a plant ...
on the tomato stem effectively blocks the dodder from attaching to the stem.


Prevention and treatment

Many countries have laws prohibiting import of dodder seed, requiring crop seeds to be free of dodder seed contamination. Before planting, all clothes should be inspected for dodder seed when moving from an infested area to a non-infested crop. When dealing with an infested area, swift action is necessary. Recommendations include planting a non-host crop for several years after the infestation, pulling up host crops immediately, particularly before the dodder produces seed, and use of preemergent herbicides such as Dacthal in the spring. Examples of non-host crops include
grass Poaceae () or Gramineae () is a large and nearly ubiquitous family of monocotyledonous flowering plants commonly known as grasses. It includes the cereal grasses, bamboos and the grasses of natural grassland and species cultivated in lawns a ...
es and many other
monocotyledon Monocotyledons (), commonly referred to as monocots, ( Lilianae '' sensu'' Chase & Reveal) are grass and grass-like flowering plants (angiosperms), the seeds of which typically contain only one embryonic leaf, or cotyledon. They constitute one ...
s. If dodder is found before it chokes a host plant, it may be simply removed from the soil. If choking has begun, the host plant must be pruned significantly below the dodder infestation, as dodder is versatile and able to grow back from its
haustoria In botany and mycology, a haustorium (plural haustoria) is a rootlike structure that grows into or around another structure to absorb water or nutrients. For example, in mistletoe or members of the broomrape family, the structure penetrates th ...
.


Use in Chinese traditional medicine

''C. chinensis'' seeds () have long been used for
osteoporosis Osteoporosis is a systemic skeletal disorder characterized by low bone mass, micro-architectural deterioration of bone tissue leading to bone fragility, and consequent increase in fracture risk. It is the most common reason for a broken bone a ...
in China and some other Asian countries. ''C. chinensis'' is a commonly used
traditional Chinese medicine Traditional Chinese medicine (TCM) is an alternative medical practice drawn from traditional medicine in China. It has been described as "fraught with pseudoscience", with the majority of its treatments having no logical mechanism of acti ...
which is believed to strengthen the liver and kidneys. Cuscuta species are also used as medicine in Himalayan regional medical traditions.


See also

* List of Cuscuta species


Gallery

File:Dodder (Cuscuta) fruit.jpg, ''Cuscuta'' sp. with a gall File:Dodder(Cuscuta)flowers.jpg, ''Cuscuta'' sp. flowers File:Cuscuta fg01.jpg, ''Cuscuta'' sp. form File:Cuscuta fg02.jpg, ''Cuscuta'' sp. form File:Dodder-vine-morris-ct-2017.jpg, ''Cuscuta'' sp. form File:Cuscuta @ThachKhê HaTinh VietNam.jpg, ''Cuscuta'' sp. form File:Dodder Forming a Net on its Host.jpg, Dodder Forming a Net on its Host File:Cuscuta in Flower, Iran.jpg, Cuscuta in Flower,
Iran Iran, officially the Islamic Republic of Iran, and also called Persia, is a country located in Western Asia. It is bordered by Iraq and Turkey to the west, by Azerbaijan and Armenia to the northwest, by the Caspian Sea and Turkmeni ...
File:Cuscuta in Iran II.jpg, How Cuscuta Attaches itself to its Host


References


Further reading

* * * * * * * * Cudney, D.W., S.B. Orloff, and J.S. Reints. 1992. An integrated weed management procedure for the control of dodder (Cuscuta indecora) in alfalfa (Medicago sativa). Weed Technology, 6, 603-606.


External links


Costea, M. 2007–onwards. Digital Atlas of Cuscuta (Convolvulaceae)
*
Flora of China: ''Cuscuta''
* Lanini, W. T., et al. Dodder. ''Pest Notes'' Jan 2002: 1–3. 15 July 2005
Online
(pdf file). * Swift, C. E. ''Cuscuta'' and ''Grammica'' species – Dodder: A Plant Parasite. ''Colorado State University Cooperative Extension''

* Dodder (''Cuscuta'' species). ''Weed Listings.'' 2005


Medicinal uses of ''Cuscuta'' in Armenia
* Chamovitz, D
Common Scents: Plants Constantly Catch a Whiff of Their Neighbors' Perfume.
''Scientific American'' May 22, 2012. {{Taxonbar, from=Q190505 Convolvulaceae genera Parasitic plants