Chromolaena odorata (L.) R.M.King & H.Rob.

King, R.M. & Robinson, H.E. (1970) Phytologia 20(3): 204. Type: .

Siam weed

Scrambling shrub to 7 m tall, often around 4 m tall. Stem round in cross-section.

Simple, entire or toothed, triangular, 4.5-12 x 20-55 mm; upperside hairy; underside densely hairy, dotted with glands visible with a hand lens. Petioles 10-17 mm long. Three conspicuous main veins running from near base to tip. Have a pungent odour when crushed. Young leaves may be partly purplish.

Inflorescence axillary or terminal panicles of heads. Flowers ca. 5 mm diameter, white, pink or purple; ray florets absent; bracts green, 2-9 mm long.

A nut, ca. 4-5 mm long, pappus of pale brown plumes.

Features not available.

An introduced species. Naturalised in NEQ and one record from CEQ in 2013, but subject to an eradication program. Altitudinal range from near sea level to 30 m. Found in and on the edges of rainforest and open forest and woodlands.

A declared noxious weed. Considered to be one of the world's worst weeds.