Pandanales, the pandans or screw-pines, is an

order Order, ORDER or Orders may refer to: * Categorization, the process in which ideas and objects are recognized, differentiated, and understood * Heterarchy, a system of organization wherein the elements have the potential to be ranked a number of ...

flowering plant Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek words ('container, vessel') and ('seed'), and refers to those plants t ...

s placed in the

monocot 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 ...

clade A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English ter ...

in the Angiosperm Phylogeny Group and

Angiosperm Phylogeny Web The Angiosperm Phylogeny Website (or APweb) is a website dedicated to research on angiosperm phylogeny and taxonomy. The site is hosted by the Missouri Botanical Garden The Missouri Botanical Garden is a botanical garden located at 4344 S ...

systems A system is a group of interacting or interrelated elements that act according to a set of rules to form a unified whole. A system, surrounded and influenced by its environment, is described by its boundaries, structure and purpose and expresse ...

. Within the monocots Pandanales are grouped in the

lilioid monocots Lilioid monocots (lilioids, liliid monocots, petaloid monocots, petaloid lilioid monocots) is an informal name used for a grade (grouping of taxa with common characteristics) of five monocot orders ( Petrosaviales, Dioscoreales, Pandanales, ...

where they are in a sister group relationship with the Dioscoreales. Historically the order has consisted of a number of different families in different systems but modern classification of the order is based primarily on

molecular phylogenetics Molecular phylogenetics () is the branch of phylogeny that analyzes genetic, hereditary molecular differences, predominantly in DNA sequences, to gain information on an organism's evolutionary relationships. From these analyses, it is possible to ...

despite diverse morphology which previously placed many of the families in other groupings based on apparent similarity. Members of the order have a subtropical distribution and includes trees, shrubs, and

vines A vine (Latin ''vīnea'' "grapevine", "vineyard", from ''vīnum'' "wine") is any plant with a growth Habit (biology), habit of trailing or wikt:scandent, scandent (that is, climbing) stems, lianas or runners. The word ''vine'' can also refer to ...

as well as herbaceous plants. The order consists of 5 families, 36 genera and about 1,610

species In biology, a species is the basic unit of 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 individuals of the appropriat ...

Description

Pandanales are highly diverse including large arboraceous plants of tropical rainforests and coastal areas, climbing

and lianas, as well as very small achlorophyllous (mycoheterotrophic) and saprophytic herbaceous forest floor species. This has made it difficult to reliably define synapomorphies, but the loss of

trimery Merosity (from the greek "méros," which means "having parts") refers to the number of component parts in a distinct whorl of a plant structure. The term is most commonly used in the context of a flower where it refers to the number of sepals in a ...

distinguishes many of them from other lilioid monocots. The Pandanales order is distinctive with its highly variable and hardly definable floral morphology, especially the number of stamens and their structure as well as many other characteristics. In some of the members, different interpretations exist regarding the composition and organization of the reproductive structures. The order includes plants with traits that seem atypical when compared to other groups of monocots. A good example is the female reproductive organ and its position relative to other parts of the

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 ...

. Some of the species included in the families

Pandanaceae Pandanaceae is a family of flowering plants native to the tropics and subtropics of the Old World, from West Africa through the Pacific. It contains 982 known species in five genera, of which the type genus, ''Pandanus'', is the most important ...

and

Stemonaceae The Stemonaceae are a family of monocotyledonous flowering plants placed in the order Pandanales. The family consists of four genera with ca 37 known species distributed in areas with seasonal climate across Southeast Asia and tropical Australia ...

show flowers formed from only one carpel, while in the Triuridaceae, a family that lacks

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 ...

, the carpels are free from each other. In fact, the Triuridaceae possess the least "typical" flower morphology in the order.

Taxonomy

History

The components of the order ''sensu'' APG have been difficult to place consistently, and historically have been associated with a number of other groupings. The Bentham & Hooker system (1883) had a similar order under the name Nudifloreae, incorporating: * Pandaneae * Cyclanthaceae * Typhaceae *

Aroideae Aroideae is a subfamily of flowering plants in the family Araceae. It is the largest subfamily in Araceae and consists of about 72 different genera, and 2,300 species. Many Aroideae have spiny pollen grains without a sporopollenin 270px, SEM ...

Lemnaceae Lemnoideae is a subfamily of flowering aquatic plants, known as duckweeds, water lentils, or water lenses. They float on or just beneath the surface of still or slow-moving bodies of fresh water and wetlands. Also known as bayroot, they arose fr ...

The Wettstein system (1935) placed the order in class Monocotyledones and used a different circumscription, incorporating: *

Sparganiaceae Sparganiaceae is a family of flowering plants. Such a family was previously recognized by most taxonomists. The APG II system, of 2003 (unchanged from the APG system, 1998), also recognizes this family, and assigns it to the order Poales in the c ...

* Typhaceae The Cronquist system (1981) placed the order in subclass

Arecidae Arecidae is a botanical name at the rank of subclass. Circumscription of the subclass will vary with the taxonomic system being used (there are many such systems); the only requirement being that it includes the family Arecaceae. Arecidae in t ...

in class Liliopsida monocotyledonswith only one family: *

In the classification system of Dahlgren the Pandanales were in the superorder Pandaniflorae (also called Pandananae) with the single family Pandanaceae.

Angiosperm Phylogeny Group

The

APG III system The APG III system of flowering plant classification is the third version of a modern, mostly molecular-based, system of plant taxonomy being developed by the Angiosperm Phylogeny Group (APG). Published in 2009, it was superseded in 2016 by a fu ...

(2009) places the Pandanales in the monocots. Both the APG III and APG II systems include five families in this order. Since the morphology of the order varies on such scale, its classification and phylogeny are based on genetic analyses. Inside the order, some doubt remains about the position of the entirely mycoheterotrophic family Triuridaceae, since it is the only one on which genetic analyses have not yet been applied. With high probability, the family may be sister to the Velloziaceae, but similarities with the family Zingiberaceae (which is a part of a whole different order – Zingiberales) do not exclude the chance for a different phylogeny. The family Velloziaceae on its own is placed at the base of the tree. The

and Cyclanthaceae are sister groups, and they form a clade which on its own is sister to the

(a family composed of two more clades).

Evolution

The order Dioscoreales holds sister relationship with Pandanales by diverging from them around 121 million years ago in the mid-

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of ...

. The formation of the crown groups took place with a difference of 2 million years between the orders - 116 Mya for the Dioscoreales and 114 Mya for the Pandanales. However, the stem group of the Pandanales is much older and goes back to 130 Mya in the early

.Merckx. Diversification of myco-heterotrophic angiosperms: Evidence from Burmanniaceae. BMC Evolutionary Biology 2008
/ref>

Phylogeny

Subdivision

The composition of the order in APG III and APG II were slightly from that in the 1998 APG system, which used the circumscription * Cyclanthaceae *

* Velloziaceae APG III includes the following families; * Cyclanthaceae *

* Triuridaceae * Velloziaceae

Distribution

The order contains members mainly distributed in all the

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 ...

and

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 ...

regions of the world, both New and Old World (including

Africa Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area ...

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the sou ...

Australia Australia, officially the Commonwealth of Australia, is a sovereign country comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands. With an area of , Australia is the largest country by ...

and

Asia Asia (, ) is one of the world's most notable geographical regions, which is either considered a continent in its own right or a subcontinent of Eurasia, which shares the continental landmass of Afro-Eurasia with Africa. Asia covers an are ...

). Also, a species is present in

China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's List of countries and dependencies by population, most populous country, with a Population of China, population exceeding 1.4 billion, slig ...

Ecology

The species are members of various ecological groups, including tropical shrubs, lianas and trees, xerophytic plants, mycoheterotrophs, as well as different herbaceous representatives.

Uses

Several species in this order produce strap-like leaves used for basketry and mats; ''

Pandanus ''Pandanus'' is a genus of monocots with some 750 accepted species. They are palm-like, dioecious trees and shrubs native to the Old World tropics and subtropics. The greatest number of species are found in Madagascar and Malaysia. Common name ...

'' (Pandanaceae) is used across

Oceania Oceania (, , ) is a geographical region that includes Australasia, Melanesia, Micronesia, and Polynesia. Spanning the Eastern and Western hemispheres, Oceania is estimated to have a land area of and a population of around 44.5 million ...

for thatch, basketry, and to make cloth, and '' Carludovica palmata'' (Cyclanthaceae) leaves are made into Panama hats. Other members as '' Stemona'' are present in

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 ...

and possess medical properties. Some species are used as insecticides. Some species of ''Pandanus'' are used as ornamentals. '' Pandanus amaryllifolius'' is a common food

flavoring A flavoring (or flavouring), also known as flavor (or flavour) or flavorant, is a food additive used to improve the taste or smell of food. It changes the perceptual impression of food as determined primarily by the chemoreceptors of the g ...

Southeast Asia Southeast Asia, also spelled South East Asia and South-East Asia, and also known as Southeastern Asia, South-eastern Asia or SEA, is the geographical south-eastern region of Asia, consisting of the regions that are situated south of mainland ...

and

karuka The karuka (''Pandanus julianettii'', also called karuka nut and ''Pandanus'' nut) is a species of tree in the family Pandanaceae and an important regional food crop in New Guinea. The nuts are more nutritious than coconuts, and are so popul ...

(''Pandanus julianettii'') is a staple food in

New Guinea New Guinea (; Hiri Motu: ''Niu Gini''; id, Papua, or , historically ) is the world's second-largest island with an area of . Located in Oceania in the southwestern Pacific Ocean, the island is separated from Australia by the wide Torres ...

References

Bibliography

* *

External links

Merckx V. Cretaceous Origins of Myco-Heterotrophic Lineages in Dioscoreales. 2010

* ttp://www.mobot.org/MOBOT/Research/APweb/orders/pandanalesweb.htm#Pandanales Angiosperm Phylogeny Web: Pandanales
Berry, PE. Pandanales. Encyclopædia Britannica 2016
* * {{Taxonbar, from=Q269303 Angiosperm orders Extant Aptian first appearances