Trichopus zeylanicus Gaertn.

Glabrous, preserving through life the habit of the first-year seedling of Dioscorea, which lies in the arrest of the second leaf of a stem to the advantage of the first. In the surface soil a rather dry, 1-4 cm long rhizome with occasional branching, ascending slightly at the apex and dying behind, losing its scale-like leaves before death, coated with chaffy very acute scale-leaves up to 5 mm long. Stems 5-7(-20), erect or ascending, to 12 cm below the solitary leaf, with c. 7 low ridges. Fertile branch with distichous scale-leaves similar to those on the rhizome but shorter, with flower buds in their axils, the whole looking like a spikelet of Brornus. Flowers extruded from between the protecting scale-leaves one at a time until 1 or 2 are pollinated whereupon those following are arrested. Leaf (in Malaysia) always cordate-sagittate, 10 by 4 cm, primary nerves 5-7, 3 reaching the blunt apex, the outer being in the margin. Blade shortly acuminate below the apex; margin undulate; petiole usurping the line of the stem by pushing the fertile branch to one side, vertical (in Malaysia). Pedicels to 7 cm long, nodding, dull purple with a greenish colour towards the base. Tepals (in Malaysia) to 1 cm long. Stamens 6, anthers raised on short zigzag filaments widening into broad connectives with the anthers edge to edge and making a roof over a chamber into which pollinating insects should enter; beyond the anthers the filament is prolonged into a process which projects forwards between the stigmas. Style stout. Fruit 3-winged, wings thick instead of flat as in Dioscorea, to 13 by 6 mm, somewhat trapezoid by reason of the way in which they narrow towards the apex and the base of the fruit, broadest above mid-length. Seeds upwards of 6 freed by the fruit walls breaking irregularly, wingless, flat, more so on one side than on the other, and differently invaginated.

In Ceylon it grows in lowland sandy forest near streams and in the Malay Peninsula in lowlying forest. In these places it is liable to be flooded; but that similar conditions rule where it grows (at about 1000 m alt.) in S. India is not known.In Ceylon and the Malay Peninsula the dispersal of the seeds is undoubtedly by sudden floods which break the fruit from its slender peduncle and carry it away. The upright position of the leaf blades as seen in Malaya is doubtless a reaching out for light from above, for when the plant was grown in a glass house at Kew, their poise was less upright (see Bot. Mag. t. 7350); moreover, herbarium specimens from Ceylon show that the poise may differ. It is not known if the flower is scented.