Burrs, flower groups, and leaves. Australian Plant Image Index, photo: Murray Fagg, banks of Snowy River, NSW

Burrs and leaves. Australian Plant Image Index, photo: Murray Fagg, Yathong Nature Reserve, near Mt Hope, NSW

Flowers and leaves. Australian Plant Image Index, photo: Murray Fagg, ACT

Plant. Australian Plant Image Index, photo: Murray Fagg, ACT

Common Name

Noogoora Burr, Cockle Burr, Californian Burr, Clotburr

Family

Asteraceae

Notes

Introduced annual forb to 4m tall.  Lowermost leaves opposite each other, other leaves alternating up the stems, cordate at the base, 4-20cm long, 30-180mm wide, flat, rough, lobed and toothed.  Individual flower heads small (less than 3mm across), male and female flowers on the same plant. Male flower heads globular, in groups of 1-7, at the tops of the stems. Female flower heads oval, in groups of 1-12, at the bases of the leaves. Burr hairy to sticky hairy when young, with many hooked spines, and two longer stout spines at the top.  Noxious weed Wentworth Shire.  Declared plant in SA.  Noxious weed in Vic. 

Descriptions and photo (as Xanthium occidentale and Xanthium orientale) in G.M. Cunningham, WE Mulham, PL Milthorpe and J H Leigh (1981 and later printings) Plants of Western New South Wales pages 726-727

PlantNET descriptions (as Xanthium occidentale and Xanthium orientale):   http://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&lvl=sp&name=Xanthium~occidentale

http://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&lvl=sp&name=Xanthium~orientale

Weeds of Australia Biosecurity Queensland Edition description (as Xanthium occidentale):  http://keyserver.lucidcentral.org/weeds/data/03030800-0b07-490a-8d04-0605030c0f01/media/Html/Xanthium_occidentale.htm