Editing Cucurbitales (section)

== Overview ==
The Cucurbitales are an order of plants with a cosmopolitan distribution, particularly diverse in the [[tropics]].<ref name=autogenerated1>{{cite journal | vauthors = Schaefer H, Renner SS | year = 2011 | title = Phylogenetic relationships in the order Cucurbitales and a new classification of the gourd family (Cucurbitaceae) | journal = [[Taxon (journal)|Taxon]] | volume = 60 | issue = 1 | pages = 122–138 | doi =  10.1002/tax.601011| jstor = 41059827 }}</ref> Most are herbs, climber herbs, woody lianas or shrubs but some genera include canopy-forming evergreen [[Laurel forest|lauroid]] trees.<ref name=autogenerated1 /><ref>{{cite web|url=http://www.florachilena.cl/Niv_tax/Angiospermas/Ordenes/Curcubitales/Cucurbitales.htm |title=Cucurbitales |publisher=Florachilena.cl |access-date=2012-03-07}}</ref> Members of the Cucurbitales form an important component of low to montane tropical forest with greater representation in terms of the number of species. Although not known with certainty the total number of species in the order, conservative estimates indicate about 2600 species worldwide, distributed in 109 genera.<ref name=autogenerated1 /> Compared to other flowering plant orders, the taxonomy is poorly understood due to their great diversity, difficulty in identification, and limited study.

The order Cucurbitales in the eurosid I clade comprises almost 2600 species in 109 or 110 genera in eight families, tropical and temperate, of very different sizes, morphology, and ecology.<ref name=autogenerated1 /> It is a case of [[divergent evolution]]. In contrast, there is [[convergent evolution]] with other groups not related due to ecological or physical drivers toward a similar solution,  including [[analogous structures]].
Some species are trees that have similar foliage to the [[Lauraceae|true laurels]] due to convergent evolution.<ref name=autogenerated1 />

The patterns of speciation in the Cucurbitales are diversified in a high number of species. They have a pantropical distribution with centers of diversity in Africa, South America, and Southeast Asia. They most likely originated in West [[Gondwana]] 67–107 million years ago, so the oldest split could relate to the break-up of Gondwana in the middle Eocene to late Oligocene, 45–24 million years ago. The group reached their current distribution by multiple intercontinental dispersal events. One factor was product of aridification, other groups responded to favorable climatic periods and expanded across the available habitat, occurring as opportunistic species across wide distribution; other groups diverged over long periods within isolated areas.<ref name=autogenerated1 />

The Cucurbitales comprise the families: [[Apodanthaceae]], [[Anisophylleaceae]], [[Begoniaceae]], [[Coriariaceae]], [[Corynocarpaceae]], [[Cucurbitaceae]], [[Tetramelaceae]], and [[Datiscaceae]].<ref>{{cite web |url=http://www.sib.gov.ar/taxonomia/orden/cucurbitales |title=Taxonomía Cucurbitales |publisher=SIB |access-date=2012-03-07 |archive-url=https://web.archive.org/web/20120406203225/http://www.sib.gov.ar/taxonomia/orden/cucurbitales |archive-date=2012-04-06 |url-status=dead }}</ref> Some of the synapomorphies of the order are: leaves in spiral with secondary veins palmated, calyx or perianth valvate, and the elevated stomatal calyx/perianth bearing separate styles. The two whorls are similar in texture.<ref>{{cite web|url=http://www.thecompositaehut.com/www_tch/webcurso_spv/ordenes_pv/cucurbitales.html |title=Laboratorio de Sistemática de Plantas Vasculares &#124; Curso SPV &#124; Prácticos &#124; Plantas Vasculares &#124; Cucurbitales |publisher=Thecompositaehut.com |access-date=2012-03-07}}</ref>

''[[Tetrameles nudiflora]]'' is a tree of immense proportions of height and width; [[Tetramelaceae]], [[Anisophylleaceae]], and [[Corynocarpaceae]]<ref>{{cite web|url=https://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=18875 |title=ITIS Standard Report Page: Corynocarpus laevigatus |publisher=Itis.gov |access-date=2012-03-07}}</ref> are tall canopy trees in temperate and tropical forests. The genus ''[[Dendrosicyos]]'', with the only species being the cucumber tree, is adapted to the arid semidesert island of [[Socotra]]. Deciduous perennial Cucurbitales lose all of their [[leaves]] for part of the year depending on variations in rainfall. The leaf loss coincides with the [[dry season]] in tropical, subtropical and arid regions. In [[temperate]] or [[polar climate]]s, the dry season is due to the inability of the plant to absorb water available in the form of ice. [[Apodanthaceae]] are obligatory endoparasites that only emerge once a year in the form of small flowers that develop into small berries, however taxonomists have not agreed on the exact placement of this family within the Cucurbitales.
Over half of the known members of this order belong to the greatly diverse begonia family Begoniaceae, with around 1500 species in two genera. Before modern DNA-molecular classifications, some Cucurbitales species were assigned to orders as diverse as [[Ranunculales]], [[Malpighiales]], [[Violales]], and [[Rafflesiales]]. Early molecular studies revealed several surprises, such as the nonmonophyly of the traditional [[Datiscaceae]], including ''[[Tetrameles]]'' and ''[[Octomeles]]'', but the exact relationships among the families remain unclear.<ref name=autogenerated1 />
The lack of knowledge about the order in general is due to many species being found in countries with limited economic means or unstable political environments, factors unsuitable for plant collection and detailed study. Thus the vast majority of species remain poorly determined, and a future increase in the number of species is expected.