Pandanales

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Pandanales
Temporal range: Mid Cretaceous – Recent 114–0Ma
Carludovica palmata starr 030807 0128.jpg
Carludovica palmata
Scientific classification
Kingdom: Plantae
(unranked): Angiosperms
(unranked): Monocots
Order: Pandanales
R.Br. ex Bercht. & J.Presl[1]
Families

Pandanales is an order of flowering plants placed in the monocot clade.

Distribution and ecology[edit]

The order contains members mainly distributed in all the tropical regions of the world (including Africa, South America, Australia and Asia).[2] There is also a species present in China. The species are members of various ecological groups, including tropical shrubs, lianas and trees, xerophytic plants, myco-heterotrophs as well as different herbaceous representatives.

Morphology[edit]

Pandanales is an order distinctive with its highly variable and hardly definable morphology of the flower,[2] especially the number of stamens and their structure so as many other characteristics. In some of the members there are even different interpretations about the composition and organization of the reproductive structures. The structure of the inflorescence also varies.

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. Some of the species included in the families Pandanaceae and Stemonaceae show flowers formed from only one carpel, while in Triuridaceae, a family that lacks chlorophyll, the carpels are free from each other. In fact, Triuridaceae holds the most doubtful flower morphology from the whole order.

Evolution and phylogeny[edit]

Since the morphology of the order varies on such scale, its classification and phylogeny are based on genetic analyses.[3] It is found that order Dioscoreales holds sister relationship with Pandanales by diverging from them around 121 millions of years ago in Mid Cretaceous. The formation of the crown groups took place with a difference of 2 millions of years between the orders - 116 Mya for Dioscoreales and 114 Mya for Pandanales. However the stem group of Pandanales is much older and goes back to 130 Mya in Early Cretaceous.[4]

Inside the order, a bit of doubt remains about the position of the entirely myco-heterotrophic family Triuridaceae, since it is the only one on which genetic analyses are not applied. There is a very high probability that the family may be sister to Velloziaceae, but similarities with Zingiberaceae family (which is a part of a whole different order – Zingiberales) do not exclude the chance for a different phylogeny. Velloziaceae on its own is placed at the base of the tree. Pandanaceae and Cyclanthaceae are sister groups, and they form a clade which on its own is sister to Stemonaceae (a family composed of two more clades).



Dioscoreales


Pandanales

Velloziaceae



Triuridaceae




Stemonaceae




Pandanaceae



Cyclanthaceae






Classification[edit]

The APG III system (2009) places the Pandanales in the monocots. Both the APG III and APG II systems include five families in this order:[1]

Uses[edit]

Several species in this order produce strap-like leaves that are used for basketry; Pandanus (Pandanaceae) is used across Oceania for thatch, basketry, and to make cloth, and Carludovica palmata (Cyclanthaceae) leaves are made into Panama hats. Other members as Stemona are present in the Traditional Chinese medicine and possess medical properties. Some species are used as insecticides.

Older classifications[edit]

The circumscriptions in APG III and APG II change slightly from that in the 1998 APG system, which used the circumscription:[1]

The Cronquist system (1981) placed the order in subclass Arecidae in class Liliopsida [=monocotyledons] with only one family:

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

The Bentham & Hooker system (1883) had a similar order under the name Nudifloreae, incorporating:

References[edit]

External links[edit]