Alternanthera Forssk.

Perennial herbs with a slender tap root; stems prostrate to erect, 2.0–3.5 mm diam., green and flushed pink, glabrous to sparsely hairy, with two decurrent lines of hairs, nodes tomentose. Leaves (20–)30–83 × 6–12 mm, leaves usually narrowly elliptic or lanceolate, sometimes linear to linear- oblong, light green or yellow-green with midrib and lateral veins pink, glabrate to sparsely hairy on margins, midrib, and both surfaces, apex acute; margins distinctly denticulate; base attenuate. Spikes globular or shortly oblong, 0.5–0.8 mm diam., clustered, with 15–20 flowers; rachis sparsely hairy, flowers subtended by 1 bract and 2 bracteoles; bracts and bracteoles 1.5–2.0 × 0.6–0.8 mm, lanceolate, cream, glabrous, membranous, shortly acuminate to acute. Perianth segments 2.3–2.4 × 0.6–0.8 mm, lanceolate, cream, glabrous, membranous, shortly acuminate to acute; anthers c. 0.15 mm long, yellow; filaments 3–4 mm long, translucent; style 0.1– 0.2 mm long; stigma capitate; ovary 0.4–0.5 mm long, green. Fruit 1.7–1.8 × 1.9–2.1 mm, cream and flushed pink, obovoid, compressed, indehiscent. Seeds 0.9–1.0 × 0.8–0.9 mm, cream to yellow, often with a light brown centre, compressed.

[Reproduced from Heenan & de Lange (2004, New Zealand J. Bot. 42: 739-745) with permission from The Royal Society of New Zealand.]