Worldwide distribution. In Australia, Fiji, French Polynesia, Samoa.
Aggressive, invasive weed of annual crops (maize, soybean, rice), plantations (sugarcane, rubber, tea), orchards, riverbanks, roadsides. A weed of cassava and taro in Pacific islands.
Stems, erect or spreading, up to 1m, square, narrowly 'winged', woody at base, sometimes rooting. Leaves, broad, hairy, oval, leaf stalks absent or short; stipules with bristles. Flowers, in leaf axils and terminal, white, blue or mauve petals fused to form 5mm long tube. Fruit covered in white hairs. Seeds smooth with cavity. Long flowering time.
Spread: seed contaminant of grain, livestock feed, plant nursery materials.
Biosecurity: regulate imports of seeds, feeds and plant introductions.