Dioscoreales
Channel: 宇宙のすべての知識 プリンシピア
Date: 2019-02-02

Dioscoreales, by Wikipedia https://en.wikipedia.org/wiki?curid=7995 / CC BY SA 3.0

#Dioscoreales
#Angiosperm_orders
#Aptian_first_appearances
#Extant_Early_Cretaceous_first_appearances
Dioscoreales

The Dioscoreales are an order of monocotyledonous flowering plants in modern classification systems, such as the Angiosperm Phylogeny Group and the Angiosperm Phylogeny Web. Within the monocots Dioscoreales are grouped in the lilioid monocots where they are in a sister group relationship with the Pandanales. Of necessity the Dioscoreales contain the family Dioscoreaceae which includes the yam ("Dioscorea") that is used as an important food source in many regions around the globe. Older systems tended to place all lilioid monocots with reticulate veined leaves (such as Smilacaceae and Stemonaceae together with Dioscoraceae) in Dioscoreales. As currently circumscribed by phylogenetic analysis using combined morphology and molecular methods, Dioscreales contains many reticulate veined vines in Dioscoraceae, it also includes the myco-heterotrophic Burmanniaceae and the autotrophic Nartheciaceae. The order consists of three families, 22 genera and about 850 species.

Dioscoreales are vines or herbaceous forest floor plants. They may be achlorophyllous or saprophytic. Synapomorphies include tuberous roots, glandular hairs, seed coat characteristics and the presence of calcium oxalate crystals. Other characteristics of the order include the presence of saponin steroids, annular vascular bundles that are found in both the stem and leaf. The leaves are often unsheathed at the base, have a distinctive petiole and reticulate veined lamina. Alternatively they may be small and scale-like with a sheathed base. The flowers are actinomorphic, and may be bisexual or dioecious, while the flowers or inflorescence bear glandular hairs. The perianth may be conspicuous or reduced and the style is short with well developed style branches. The tepals persist in the development of the fruit, wh...