Pigweed (Portulaca oleracea): Weed management guide for Australian vegetable production

Abstract

Pigweed (Portulaca oleracea) is an annual, succulent herb. It is native to either South America or North Africa, and features a thick tap root with many fibrous secondary roots, forming a prostrate mat of up to 60 cm in diameter. The stem of pigweed is often reddish, succulent, and commonly with several degrees of branching observed from the main stem. Leaves are alternate and are often clustered at branch tips. They are smooth, succulent, thick, shiny, and are narrow at the base with broad, rounded ends, ranging from 2 to 13 mm in width and 4 to 28 mm in length. Flowers are pale yellow, around 4 mm long, and comprised of 4 to 6 petals. Fruit is a globular pointed capsule, 4 to 9 mm in diameter, and contains many tiny brown to black seeds, which are shiny and 0.5 to 0.8 mm in diameter. Pigweed is also sometimes known as 'purslane'. It is a distinctive weed species and most vegetable farmers will be familiar with it, however it may be possible to confuse it with 'giant pigweed' (Trianthema portulacastrum), particularly soon after germination. Also known as black pigweed, this species is considered a native of tropical areas, and in Australia is largely found in the Northern Territory, Queensland, and northern New South Wales. As an adult plant, giant pigweed may be distinguished from pigweed by its more rounded, crinkled leaves and pink flowers.