Alternanthera pungens (AMARANTHACEAE) Khaki Weed

Weeds to Whack

Khaki weed Alternanthera pungens is a widespread weed native to South America. Pungens means sharp. The plant is spread readily by its many white-yellow prickly burrs carried by contact with animals and people. Grows in dense patches flat on the ground. It is able to survive dry periods. Prostrate, reddish stems are produced from a central crown often take root at the nodes, that is it produces adventitious roots. There are short, soft hairs on the stems and sometimes on the leaf stalks (petioles). Leaf blades are ovate (egg-shaped) or oval (elliptic) in shape. These paired leaves differ in size (one leaf of the pair is significantly larger than its partner) and the leaf margins are somewhat wavy.

Photo: Sheldon Navie

Foliage, Flowers

Small flowers are grouped together on spikes. The ‘petals’ (perianth segments) are whitish or straw coloured with a sharp point at the tip, 5-7 mm long. Barbed hairs are found at the base of the perianth segments. These segments become hardened and form prickles as they age. Flowering occurs from spring to autumn. The small fruit is about 1 mm long with a truncate apex. Not noxious in Queensland, but declared in Victoria, New South Wales, South Australia and the Northern Territory. Also prohibited entry into Western Australia.
Photo: Sheldon Navie