Eastern St Paul's-wort

Sigesbeckia orientalis is an annual, upright herb or subshrub, about 0.4–1.5 m (1 ft 4 in – 4 ft 11 in) high, usually multi-branched with reddish coloured, hollow stems. The leaves may be triangular-shaped, lance-shaped to broadly lance-shaped, and up to 2–17 cm (0.79–6.69 in) long, 1–7 cm (0.39–2.76 in) wide, petiole up to 2 cm (0.79 in) long, underside has small, yellow glands. The upper and lower surface of the leaf blade is sparsely hairy, the margin has pointed to rounded teeth, larger teeth nearer the base, gradually narrowing, base wedge-shaped, and rough on both surfaces. The yellow or orange flowers are borne in clusters of about 15 sessile flowers per head, about 10 mm (0.39 in) in diameter, usually containing female and hermaphrodite flowers. There are about 8 ray florets, each ligule 1–2 mm (0.039–0.079 in) long, and 10-15 disc florets. The fruit is a dark brown to black cypsela, 2–3 mm (0.079–0.118 in) long, curved and ridged. Flowering and fruiting occurs all months of the year.

Sigesbeckia orientalis has a broad distribution in Africa and Asia, but has been widely naturalised outside this range. There is debate whether the species is native to Australia.The National Herbarium of New South Wales accepts the species as native. It is a widespread species in Australia growing on river banks and on shallow, stony locations.