Common name: Perennial Ragweed
Ambrosia psilostachya DC. APNI* 
Description: Erect stout perennial herb to 2 m high, often forming extensive colonies.
Leaves alternate, lanceolate to ± ovate, 5–12 cm long, 2–4 cm wide, pinnately divided into several pointed lobes, scabrous to hirsute.
Male heads cream or green; female heads few in small clusters, with 1 floret. Bracts united to form the fruit, fruit c. 2 mm long, hairy, with 5 short spines above and a longer central beak.
Flowering: spring–summer.
Distribution and occurrence: Widespread weed of roadsides, wasteland, creek and channel banks, west to Griffith. Native of Amer.
NSW subdivisions: *NC, *CC, *NT, *CT, *NWS, *CWS, *SWS, *NWP, *SWP
Other Australian states: *Qld *Vic. *W.A. *S.A.
A declared noxious weed in some shires.
Text by L. Murray
Taxon concept: Flora of NSW 3 (1992)
APNI* Provides a link to the Australian Plant Name Index (hosted by the Australian National Botanic Gardens) for comprehensive bibliographic data
***The AVH map option provides a detailed interactive Australia wide distribution map drawn from collections held by all major Australian herbaria participating in the Australian Virtual Herbarium project.
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