Description: Annual or perennial herbs, with prostrate or ascending stems.
Inflorescence globose to ovoid, axillary or terminal, usually of 1–several spikes, these sometimes clustered. Flowers bisexual, each subtended by a small bract and 2 bracteoles. Perianth segments 5, scarious and white. Stamens 5 (or a few reduced to staminodes), fused at the base. Ovary sessile, flattened to globose; style short or not developed; stigma capitate.
Fruit indehiscent, compressed, with an apical notch, 1-seeded.
Distribution and occurrence: World: c. 200 species, tropical & subtropical regions. Australia: 8 or 9 species, all States.
Text by S. W. L. Jacobs & L. Lapinpuro
| ||Key to the species|| |
|1||Inflorescence pedunculate, axillary or terminal; peduncles to 4 cm long||Alternanthera philoxeroides|
|Inflorescence sessile, axillary||2|
|2||Perianth segments unequal; outer 2 c. 4–5 mm long, acuminate, pungent; next inner narrower, c. 3 mm, apex toothed with midrib excurrent; 2 innermost to c. 2.5 mm long, acute, sigmoid, with dorsal tuft of hairs at first bend||Alternanthera pungens|
|Perianth segments more or less equal|
Back to 1
|3||Perianth segments woolly on the midback||Alternanthera angustifolia|
|Perianth segments mostly glabrous, or sometimes with a few hairs along back of midrib|
Back to 2
|4||Perianth segments 4–5 mm long, lanceolate, with long, tapered, acute apex||Alternanthera nodiflora|
|Perianth segments 2–3 mm long, lanceolate or oblong, acute|
Back to 3
|5||Innermost bracts lanceolate, acuminate, 1.5–2.5 mm long; perianth segments lanceolate||Alternanthera denticulata|
|Innermost bracts ovate, acute, to 1.5 mm long; perianth segments oblong|
Back to 4
|6||Leaves lanceolate to oblanceolate or elliptic, 15–25 mm long, 6–10 mm wide||Alternanthera nana|
|Leaves ovate to oblong-ovate or obovate, 5–50 mm long, 3–6 mm wide|
Back to 5
|Alternanthera sp. A Flora of New South Wales (M.Gray 5187)|