Description:

• Dioecious climbers, rarely procumbent, herbaceous or partly woody, rarely monoecious or flowers bisexual, with tuberous or thick, woody or rhizomatous rootstocks above or partly below ground, or roots with tuberous swellings
• Leaves alternate or sometimes opposite, cordate, sagittate, rounded or truncate at base, entire to digitately divided
• Flowers mostly unisexual, regular, solitary, paired, or in spikes, racemes, or panicles
• Perianth 3 + 3, fused towards base; tube urn-shaped, campanulate or almost absent
• Male flowers: perianth 6-lobed or -fid; stamens 6, sometimes connate into a short column in central flowers; anthers 2-thecous with longitudinal slits, with thecae contiguous, on a broad connective produced above thecae into an elongate spathulate, horned appendage, or thecae separated; style absent or rudimentary
• Female flowers with 6 free segments; staminodes sometimes present; ovary inferior, 3-locular, sometimes 3-winged, with 2 axile ovules in each locule; styles 3, short; stigmas entire or bifid
• Fruit a 3-valved, 3-angled or 3-winged capsule, sometimes 1-seeded and indehiscent
• Seeds compressed, winged, sometimes with a much-folded testa; embryo small; endosperm copious
• x = 10 (8, 9) (aneuploids, high polyploidy)

Nomenclature:

• Dioscorea L.
  • Linnaeus: 1032 (1753)
  • Baker: 247 (1896)
  • Burkill: 319 (1960)
  • Archibald: 1 (1967)
  • Sölch: 1 (1969)
  • Wilkin: 19 (1999)
• Testudinaria Salisb.
  • Salisbury: 147 (1824)
  • Baker: 252 (1896)

Distribution & Notes:

• Global: Species ± 600, ± cosmopolitan in warm regions
• Southern Africa: Species 16, widespread