Ambrosia psilostachya
DC. Perennial RagweedErect perennial herb to 2 m high, stoloniferous, often forming dense colonies; stems simple or branched above, strigose to scabrous. Leaves alternate, subsessile, lanceolate to ovate in outline, mostly 4–12 cm long and 2–4 cm wide, pinnatipartite with lanceolate segments 2–4 mm wide, surfaces appressed-hairy. Inflorescences often numerous, 3–12 cm long. Male capitula numerous, 2–3 mm diam., cream or greenish; peduncles c. 1 mm long; florets many, not exceeding involucral bracts. Female capitula in small clusters in upper axils; fruiting capitula turbinate, 3–4 mm long, reticulate, 5-ribbed, with 5 short spines above and a longer central beak. Flowers spring and summer.
Also naturalised WA, SA, Qld, NSW. Native to North America. Known from the Corryong, Nagambie and Shepparton areas but probably more widespread. Grows along roadsides and other disturbed sites. Declared a noxious weed in Victoria.
Jeanes, J.A. (1999). Asteraceae. In: Walsh, N.G.; Entwisle, T.J., Flora of Victoria Vol. 4, Cornaceae to Asteraceae, pp. 652–666. Inkata Press, Melbourne.
Spinning
