| Classification |
| Kingdom: Plantae
Division: Magnoliophyta
Class: Liliopsida
Order Type: Basal Angiosperms-Monocots
Order: Dioscoreales
Family: Dioscoreaceae
Family Common Name: Yam Family
Genera: Dioscorea |
Defining Features: The family
has features in common with the Smilacaceae, including the climbing habit
and prickles on the stems and leaves, but has no tendrils.
Defining Morphology: Floral
Features: Inflorescences are often determinate, axillary of spikes, racemes,
panicles or solitary flowers. Flowers are often unisexual, actinomorphic
and small. Ovaries are inferior with axile placentation. Fruit and Seed
Features: Monocotyledon. Fruit a capsule, berry or samara. Seeds mostly
winged and flat. Vegetative Features: Habit as herbs, shrubs, or woody
twining vines. Plants have thick tuber-like swelling or rhizomes. Leaves
alternate, sometimes opposite, simple and net veined, estipulate. Leaves
have pulvini at both ends of the petiole or stipule-like flanges. Bulbils
may be present in leaf axile.
Distribution: Pantropical,
with a few in the temperate regions of North America, SE Asia and Europe.
Economic Use: A few species
are cultivated as the important staple, 'yams', which is an edible tuber.
Some species produce the chemical sapogenins, which is being used in oral
contraceptives and is a precursor of cortisone and progesterone.
Number of Genera Globally:
3
Number of Species Globally:
404
