Australian Tropical Rainforest Plants - Online edition
Marsdenia velutina R.Br.
Brown, R. (1810) On the Asclepiadeae : 18. Type: Northern Territory, mainland opp. Groote Eylandt, 4 Jan. 1803, R. Brown; lecto: BM. Fide P. I. Forster, Austrobaileya 3:285 (1990).
Vine stem diameters to 4 cm recorded. Dead bark layered, showing growth rings in transverse section. Exudate not copious, produced by living bark and pith. Outer blaze speckled and striped, inner blaze uniform +/- white in colour. About 2 or 3 vascular rays (segments of bark) visible in transverse sections of the stem.
Twigs and petioles produce a milky exudate. Leaf blades about 9-18 x 7.5-15 cm, petioles about 3.5-14 cm long, sometimes almost as long as the leaf blades. Lateral veins about 4-6 on each side on the midrib. Upper and lower leaf blade surfaces densely clothed in short soft hairs. Colleters (small finger-like glands) about 6-15, present on the upper surface of the midrib near its junction with the petiole. A raised line usually visible on the twigs between the attachment points of the petioles.
Inflorescence densely clothed in hairs. Calyx lobes densely hairy, about 3-3.5 x 2 mm. Corolla densely hairy on the outer surface, tube about 4 mm long, lobes about 2.5-3 x 1.5 mm. Anthers about 3 mm long with flap-like appendages at the apex and almost enclosing the stigma. Staminal corona outgrowths narrow, about 2 mm long, fitting into pockets on the inner surface of the corolla. Carpels about 1-1.2 mm long. Style about 1 mm long. Style head about 1 mm long.
Fruits ovoid to pyriform, about 5.5-7 x 2 cm, surface densely clothed in soft velvety hairs. Seeds numerous. Each seed about 7-9 x 5 mm long, plano-convex, plumes white, about 15-25 mm long, attached at one end. Testa brown on the convex side but cream on the flat side. Embryo about 7-8 mm long, radicle about 2-2.5 mm long, much shorter and narrower than the distinctly veined cotyledons which are about 5 mm long.
Cotyledons elliptic to oblong, about 15-18 x 11-13 mm, midrib depressed on the upper surface and not reaching the apex of the cotyledon. Hypocotyl hairy. First leaves ovate to cordate, apex obtuse, base truncate, obtuse or cordate, both the upper and lower surfaces and petioles densely clothed in short curved hairs. At the tenth leaf stage: leaf blade cordate to broadly lanceolate, apex acuminate to acute, base cordate. Lower surface of the leaf blade clothed in short stiff hairs, upper surface sparsely clothed in similar hairs. Petiole densely clothed in short stiff hairs. About 4-6 colleters (short finger-like glands) present on the upper surface of the leaf blade close to its junction with the petiole. Small peg-like glands resembling stipules usually visible in the axils. Seed germination time 12 to 17 days.