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. Bracts small. 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)|