Alternanthera philoxeroides

(Martius) Grisebach

Abh. Königl. Ges. Wiss. Göttingen 24: 36. 1879.

Common names: Alligatorweed
Basionym: Bucholzia philoxeroides Martius Beitr. Amarantac., 107. 1825
Synonyms: Achyranthes philoxeroides (Martius) Standley
Treatment appears in FNA Volume 4. Treatment on page 448. Mentioned on page 449.

Herbs, perennial, aquatic to semiterrestrial, stoloniferous, to 50 dm. Stems prostrate, forming mats, often fistulose, glabrous. Leaves sessile; blade narrowly elliptic, elliptic, or oblanceolate, 3.5–7.1 × 0.5–2 cm, herbaceous, apex acute to obtuse, glabrous. Inflorescences terminal and axillary, pedunculate; heads white, globose, 1.4–1.7 cm diam.; bracts not keeled, less than 1/2 as long as tepals. Flowers: tepals monomorphic, white, lanceolate or oblong, 6 mm, apex acute, glabrous; stamens 5; pseudostaminodes ligulate. Utricles not seen. Seeds not seen.

Phenology: Flowering early spring–summer.
Habitat: Ponds, ditches, streams, bayous
Elevation: 0-200 m


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Introduced; Ala., Ark., Calif., Fla., Ga., Ill., Ky., La., Miss., N.C., S.C., Tenn., Tex., Va., West Indies, native to South America.


Alternanthera philoxerioides is said to reproduce only vegetatively in North America. I have seen no fruit or seed.

Selected References


Lower Taxa

Steven E. Clemants +
(Martius) Grisebach +
Bucholzia philoxeroides +
Alligatorweed +
Ala. +, Ark. +, Calif. +, Fla. +, Ga. +, Ill. +, Ky. +, La. +, Miss. +, N.C. +, S.C. +, Tenn. +, Tex. +, Va. +, West Indies +  and native to South America. +
0-200 m +
Ponds, ditches, streams, bayous +
Flowering early spring–summer. +
Abh. Königl. Ges. Wiss. Göttingen +
Weedy +, Introduced +  and Illustrated +
Achyranthes philoxeroides +
Alternanthera philoxeroides +
Alternanthera +
species +