Weed of the Month – July 2014

STINKWORT

(Dittrichia graveolens)

(Photos: C.Schultz; Cape Jervis)

This annual is native to the Mediterranean region, but adapts to other temperate climes with a winter rainfall of 300-800mm. It likes open (unshaded), disturbed sites where there is sparse groundcover: roadsides, paddocks, wasteland and riverbanks; it also spreads into dry grasslands. If undetected or ignored, it can take over. The plant is aromatic, with an odour like camphor (hence the common name). In summer it grows rapidly from a rosette to an erect plant up to 50cm, with sticky, slightly hairy grey-green foliage. Hundreds of small yellow flowers appear from January to April, and fruits from February. These fruits produce massive numbers of seeds (about 15,000 per plant!), which are viable for 3 years. The 2mm seeds are hairy, with about 30 bristles each. These hairs allow them to cling to clothing, machinery, animal fur, etc., and hence enable seed dispersal by means other than wind and water. The plant can cause dermatitis, itchiness and blistering of your skin, so avoid touching it. Grazing animals are even worse off … ingested seeds can give them enteritis and kidney disease!

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