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Dioscorea transversa

Family

Dioscoreaceae

Botanical Name

Dioscorea transversa R.Br.

Brown, R. (1810) Prodromus Florae Novae Hollandiae: 295. Type: Northern Australia, R. Brown; holo: BM?; iso: NSW.

Synonyms

Dioscorea punctata R.Br., Prodromus Florae Novae Hollandiae: 294(1810), Type: East coast of Australia; R. Brown; holo: BM.

Common name

Long Yam; Yam, Native; Native Yam; Yam, Long; Yam

Stem

A slender vine not exceeding a stem diameter of 2 cm. Stems twining to the right.

Leaves

Leaf blades about 4.5-14 x 3-12 cm. Petioles about 2-6 cm long, thickened just prior to their junction with the twig. Elongated oil dots visible with a lens. Leaf blades 5-veined or obscurely 7-veined at the base. Small globular bulbils present in some leaf axils.

Flowers

Male flowers: Spikes about 6-7 cm long, usually about 3-5 spikes in each leaf axil. Flowers sessile, +/- globose, about 1.5 mm diam. Tepals in two similar whorls, each tepal about 1.5-2 mm long. Stamens about 0.5 mm long, fused together to form a very short column +/- attached to the base of the tepals. Female flowers: Spikes about 1.5-2.5 cm long, usually 1 or 2 spikes in each leaf axil. Flowers pleasantly perfumed, sessile, about 1.2 mm diam. Tepals in two similar whorls, the outer tepals slightly larger. Tepals about 0.8-1.1 mm long. Hypanthium 3-angled, about 2 mm long. Six minute staminodes or nectary glands visible around the base of the ovary. Style 3-armed, the arms reflexed. Ovules 2 per locule.

Fruit

Fruits 3-winged, produced in pendulous clusters. Each fruit about 15-20 x 23-26 mm. Wings rounded, about 14-16 x 12-14 mm. Seeds about 6 per fruit. Seed + wing about 15-19 x 11-16 mm. Embryo located on the margin of the seed. Embryo about 0.8-1 mm long, paddle-shaped to obpyriform. Radicle shorter than the 'cotyledon'.

Seedlings

First leaf cordate to orbicular, about 25-35 x 25-35 mm, base deeply cordate. Upper surface dark green, lower surface red to purple. About 7 depressed veins radiate from the base of the leaf blade. Petioles red, about 25-35 mm long, longitudinally ribbed with 4 or 5 ribs.

Distribution and Ecology

Endemic to Australia (?), occurs in WA, NT, CYP, NEQ and southwards as far as south-eastern New South Wales. Altitudinal range in northern Australia from near sea level to 1100 m. Grows in open forest, wet sclerophyll forest, rain forest and gallery forest.

Natural History

A decoction of this small native yam was used by Aborigines of the Tully (NEQ) district as a application for skin cancers. Cribb (1981).

WA

X

NT

X

CYP

X

NEQ

X

Slender Vine

X

RFK Code

2517