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Pachyrhizus erosus

Family

Fabaceae

Scientific Name

Pachyrhizus erosus (L.) Urb.

Urban, I. (1905) Symbollae Antillanae seu Fundamenta Florae Indiae Occidentalis : 311.

Common name

Mexican potato; Yam-bean; Potato-bean; Jicama; Ahipa

Weed

*

Stem

A slender vine not exceeding a stem diameter of 2 cm.

Leaves

Middle leaflet blade about 4.5-10 x 5-12 cm, stalk about 1.22-2.5 cm long. Lateral leaflet blades about 4.5-9 x 4.5-8 cm, stalks about 0.4-0.5 cm long. Compound leaf petiole about 3-10.5 cm long, grooved on the upper surface. Stipules about 3-4 mm long. Stipels filiform, about 3-4 mm long. Leaflet blades sparsely hairy on the underside, less hairy on the upper surface.

Flowers

Inflorescence about 5-20 cm long, flowers in clusters of up to five. Pedicels about 5 mm long. Calyx about 8-10 mm long, the lobes about 5 mm long. Petals: standard blue to purplish, about 20 x 20 mm, apex emarginate; wings and keel about 20 mm long. Stamens 10, the filaments of nine stamens fused to form a tube open on one side. One stamen free. Base of the ovary surrounded by an irregular disk about 1-1.5 mm high. Ovary about 6-7 mm long, surface clothed in hairs. Style curved, about 15 mm long. Ovules about eight to ten.

Fruit

Fruits about 10-13 x 1.3-1.5 cm, outer surface clothed in pale brown prostrate hairs. Seeds about 7-9 per fruit, each seed flat +/- knee-cap shaped (patelliform), about 9-12 mm diam. Hilum about 3 mm long. Radicle about 2 mm long, much shorter and narrower than the cotyledons.

Seedlings

Features not available.

Distribution and Ecology

An introduced species originally from tropical America, occasionally found in NEQ. Cultivated in Darwin (NT) and Broome (WA). Altitudinal range from near sea level to 750 m. Usually grows in agricultural areas rarely in rain forest situations. Also occurs in New Guinea.

Natural History & Notes

Seeds and leaves poisonous (Austin, D. F. 1998. Poisonous Plants of Southern Florida).

Unpalatable to stock. Widely cultivated in the wet tropics for its edible tubers and pods, although tubers may sometimes be toxic. Seeds have been used as fish-poison. Hacker (1990).

Shrub (woody or herbaceous, 1-6 m tall)

X

Slender Vine

X

Synonyms

Dolichos erosus L., Species Plantarum : 726(1753), Type: Plukenet, Phytogr. (Almagestum) 292, t.54, fig. 4. 1696. Fide Howard, Fl. Less. Antilles 4(1): 514. 1988.

RFK Code

2630