Known also as Porterweed, White Snakeweed is native to Mexico, Central America, the Caribbean and South America to Peru and Argentina. It is widely naturalised in North Queensland and north-western parts of the Northern Territory and occasionally naturalised in south-eastern Queensland where it is of particular concern, being one of the new and emerging invasive plant pests. White Snakeweed is an annual or perennial herb to 2 m tall, becoming somewhat woody towards the base. The leaf margins are serrate to crenate-serrate meaning like saw-teeth but somewhat rounded. Flowers are white, sometimes blue.

Photo: Craig W.

Leaves

Photo: Craig W.

Flowers on flower spike

Photo: Craig W.

Flowers on flower spike

Photo: Craig W.

Snake-like flower spike

Photo: Craig W.

Flowers closeup

Photo: Craig W.

Flowers on flower spike

Photo: Robert Whyte