Dioscorea quaternata (Walt.) J.F. Gmel. - Wild Yam

Dioscorea quaternata plant

Family - Dioscoreaceae

Stems - To +3m long, vining, twining, herbaceous, from thickened tubers, glabrous.

Leaves - Lower leaves in whorls of 4-many, petiolate, upper leaves whorled or alternate. Petioles to +6cm long, glabrous, thickened at the base. Blades cordate, entire, acute to acuminate, +/-12cm long, +/-10cm broad, typically with 9-11 veins, glabrous, shiny to dull green.

Inflorescence - Staminate inflorescences of axillary panicles to +/-10cm long. Axis of inflorescence glabrous. Each division if the panicles typically subtended by small subulate bracts. Bracts to 2mm long. Flowers sessile, typically 2 at a node. Flowers subtended by a broadly ovate bract. Bracts glabrous, scarious in the apical half, 1.2mm long and broad.
Pistillate inflorescences not seen.

Dioscorea quaternata inflorescenceStaminate inflorescence.

Flowers - Staminate flowers - Perianth segments 6, green, glabrous, spreading, obovate to elliptic, -2mm long, with slightly scarious margins. Stamens 6, adnate at the base of the perianth segments, erect. Filaments green, glabrous, short, .2-.3mm long. Anthers bi-lobed, whitish, .2-.4mm broad.
Pistillate flowers not seen.

Dioscorea quaternata flowerStaminate flower close-up.

Dioscorea quaternata fruitsFruits.

Flowering - April - June.

Habitat - Rich and/or rocky woods, talus slopes, thickets.

Origin - Native to U.S.

Other info. - This vine can be found in the southeastern corner of Missouri. The plant is easy to identify because of its whorled leaves. I did not get the chance to take pics of the pistillate inflorescences or flowers last season. Maybe this year...
Another species, D. villosa L., is very similar and many botanists think the two should be lumped as one species. Currently they are still separated on differences in their root structure and fruit size. D. villosa is also supposed to have 3 or less leaves at a node whereas D. quaternata has 4 or more. This characteristic doesn't always hold in the field however. Plants found anywhere in Missouri other than the southeast corner of the state are D. villosa.

Photographs taken in Linville, NC., 5-11-03, and at Big Spring Park, MO., 7-8-04.


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