Malvastrum americanum (L.) Torr.

Torrey, R. (1859) Report on the United States and Mexican Boundary Survey 2(1) Botany : 38. 

Spiked Malvastrum

Flowers and fruits as a shrub about 1 m tall.

Leaf blades about 1-6.4 x 0.5-3.5 cm. Stems, petioles and both the upper and lower surfaces of the leaf blade densely clothed in stellate hairs. Stipules linear, about 10 mm long, hairy.

Flowers sessile or almost sessile, about 13-15 mm diam.

Fruits about 4-4.5 mm diam, surrounded by the persistent calyx, each fruit consisting of about 7 or 8 mericarps with several hairs on one edge. Seeds about 1.5 x 1 mm, testa leathery.

Cotyledons about 6 x 6-7 mm, usually wider than long, 3-veined with the midrib and two lateral veins radiating from the base, apex rounded to retuse, base truncate. Petioles about 6-7 mm long. First pair of leaves clothed in stellate hairs, leaf blades cordate at the base. At the tenth leaf stage: both the upper and lower surfaces of the leaf blade densely clothed in stellate hairs. Stipules linear, about 5-6 mm long. Terminal buds, petioles and stem densely clothed in stellate hairs. Seed germination time 11 to 105 days.

An introduced species originally from tropical America now naturalised in WA, NT, CYP, NEQ, CEQ and southwards to all mainland states. Altitudinal range in NEQ from 340-760 m. Grows as an understory weedy plant in disturbed vine thickets and monsoon forest. Also widespread in tropical regions including America and Malesia.

Malvastrum americanum (L.) Torr. var americanum,  Hill, S.R. (1980) Brittonia 32(4): 464.  Malva americana L., Species Plantarum : 687(1753), Type: Hortus Leydensis, A. van Royen s.n.; lecto: L 908.139-311. Malvastrum americanum var. stellatum S.R.Hill, Brittonia 32(4): 464-466 (1980), Type: Australia. Queensland: Middle Percy Island, 87 mi SE of Mackay, 24 Apr 1956, M.Lazarides 5606 (holotype: BRI; isotypes: K, US).