Winged yam (Dioscorea alata) is another non-native, invasive vine in Florida. It is closely related to air potato (Dioscorea bulbifera). Covered with large leaves, it can quickly grow into the tops of tall trees. Winged yam is known to have “disprupted natural-area plant communities, particularly coastal hammocks in south Florida.” Fairly large naturalized populations occur in northern Florida.

This member of the yam family (Dioscoreaceae) produces edible underground tubers. (Though most yams contain an acrid component, cooking makes them edible.) The large underground tubers of winged yam can weigh up to 100 pounds. Like air potato, winged yam also produces large numbers of aerial tubers, which are potato-like growths attached to the stems. These grow into new plants. Dioscorea species are cultivated for their edible tubers in West Africa where they are important commodities. Uncultivated forms (as in Florida) however are reported to be bitter and even poisonous. Dioscorea varieties, containing the steroid diosgenin, are a principal material used in the manufacture of birth-control pills. Research has shown that winged yam has antifungal properties.

Winged yam is named after its “winged stem” (wide ridges along the squarish stem). (D. bulbifera has a round stem.) Winged yam has a winter dormant period when the stems die back to the ground. After dormancy, the underground tubers give rise to stems which can quickly grow to 30 feet long. The vine’s stem is herbaceous (not woody). The large leaves are up to 8 inches long and are heart-shaped (cordate). The leaf blade’s basal lobes are rounded, and its leaf veins radiate from a single point. The leaves have long stems (petioles), and are opposite on the stem. (On D. bulbifera, leaves are alternate on the stem.) Winged yam flowers hang in relatively long clusters (panicles and spikes) up to 1 foot long. The fruit is a 3-part capsule of winged seeds. Winged yam plants produce aerial tubers that are attached closely to the stems where leaves attach to the stem (axil). These aerial tubers are greyish-brown and somewhat irregular with a rough, bumpy surface. In addition to the aerial tubers, edible underground tubers may weigh up to 100 pounds.

Appearance

Vigorously twining herbaceous vine, from massive underground tuber.

Leaves

Long petioled, opposite (often with only one leaf persistent); blades to 20 cm (8 in) or more in length, narrowly heart shaped, with basal lobes often angular.

Flowers

Small, occasional, male and female arising from leaf axils on separate plants (i.e., a dioecious species); male flowers in panicles to 30 cm (1 ft) long; female flowers in smaller spikes.

Fruit

A 3-parted capsule; seeds winged.

Ecological threat

Some stands forming blankets of shingled leaves over native vegetation and able to cover even mature trees. FLEPPC Category I

Distribution

NW, NE, C, SW, SE

Text from Invasive and Non-Native Plants You Should Know, Recognition Cards, by A. Richard and V. Ramey, 2007. UF/IFAS Center for Aquatic and Invasive Plants, Publ. No. SP 431.

View more information and pictures about the winged yam vine, as contained in the Langeland/Burks book, Identification & Biology of Non-Native Plants in Florida’s Natural Areas.

View the herbarium specimen image from the University of Florida Herbarium Digital Imaging Projects.

Financial support for this web page provided by the St. Johns River Water Management District (FL).

Citations

1. Identification and Biology of Nonnative Plants in Florida’s Natural Areas – Second Edition,
by K.A. Langeland, H.M. Cherry, et al. University of Florida-IFAS Publication # SP 257. 2008.

2. Invasive and Non-native Plants You Should Know – Recognition Cards,
by A. Richard and V. Ramey. University of Florida-IFAS Publication # SP 431. 2007.

3. Integrated Management of Nonnative Plants in Natural Areas of Florida, by K. A. Langeland, J. A. Ferrell, B. Sellers, G. E. MacDonald, and R. K. Stocker. University of Florida-IFAS Publication # SP 242. 2011.

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