Thunbergia arnhemica F.Muell.

Acanthaceae

Mueller, F.J.H. von (1875) Fragmenta Phytographiae Australiae 9: 73. Type: Prope portum Darwini; Schultz, 17.

Usually a slender vine.

Leaf blades about 4-8.5 x 2-5 cm, petioles about 0.8-2 cm long, grooved or channelled on the upper surface. Lateral veins 3-5 on each side of the midrib, forming loops inside the margin of the leaf blade at least in the apical half. Both the upper and lower leaf blade surfaces clothed in hairs. Each lobe at the base of the leaf blade usually ends in a tooth or acuminate tip. Leaf-bearing twigs 4-angled, densely clothed in hairs. Twigs or stems clothed in short, translucent, backward-pointing hairs.

Flowers usually solitary in each leaf axil on stalks about 4.5-14 cm long. Each flower about 4 cm diam., subtended by two large leafy bracts about 15-20 x 10 mm. Calyx tube about 1 mm long, lobes 10-20, each about 1-2 mm long. Corolla tube about 20 mm long, lobes about 18-25 x 20 mm. Stamens attached near the base of the corolla tube. Anthers about 2-3 mm long, filaments about 3-4 mm long. Ovary laterally compressed and ribbed. Style about 18 mm long, as long as the corolla tube or slightly exceeding it. Stigma 2-lobed, appressed to form a shallow or deep cup. Ovules two per locule

Fruits +/- globose at the base, about 8-13 mm diam. with a beak-like extension about 10-14 mm long at the apex. Fruiting pedicels about 8 mm long with the calyx lobes persistent at the apex. Seeds globular, about 4-5 mm diam., testa surface rugose for some part. Cotyledons unequal in size, one +/- enclosing the other with the smaller one on the outer surface. Placenta +/- globular, somewhat enlarged forming a cavity in the larger cotyledon.

Features not available.

Occurs in WA, NT, CYP, NEQ and CEQ. Altitudinal range from near sea level to 500 m. Usually grows in open forest but also found in monsoon forest and rain forest margins. Also occurs in New Guinea.

Flowers profusely during the wet but can be almost impossible to find in the dry season.

Thunbergia powellii F.Muell., Southern Science Record : 34(1882), Type: Among a small lot of dried plants, recently received from Mr. Walter Powell, and collected by him in Goode Island. Thunbergia fragrans C.Presl, Botanische Bemerkungen : 94(1845), Type: Drege pl. cap. Thunbergia powellii F.Muell., Systematic Census of Australian Plants : 99(1883), Type: Among a small lot of dried plants, recently received from Mr. Walter Powell, and collected by him in Goode Island.