Alternanthera philoxeroides (Mart.) Griseb.
  • Abh. Königl. Ges. Wiss. Göttingen
  • Alligatorweed

Cite taxon page as 'WFO (2021): Alternanthera philoxeroides (Mart.) Griseb. Published on the Internet; Accessed on: 18 Sep 2021'

General Information

Herbs perennial. Stem ascending from a creeping base, 55-120 cm, branched; young stem and leaf axil white hairy; old ones glabrous. Petiole 3-10 mm, glabrous or slightly hairy; leaf blade oblong, oblong-obovate, or ovate-lanceolate, 2.5-5 × 0.7-2 cm, glabrous or ciliate, adaxially muricate, base attenuate, margin entire, apex acute or obtuse, with a mucro. Heads with a peduncle, solitary at leaf axil, globose, 0.8-1.5 cm in diam. Bracts and bracteoles white, 1-veined, apex acuminate; bracts ovate, 2-2.5 mm; bracteoles lanceolate, ca. 2 mm. Tepals white, shiny, oblong, 5-6 mm, glabrous, apex acute. Filaments 2.5-3 mm, connate into a cup at base; pseudostaminodes oblong-linear, ca. as long as stamens. Ovary obovoid, compressed, with short stalk. Fruit not known. Fl. May-Oct. 2n = 100*.

  • Provided by: [G].Flora Of CHina @
    • Source: [
    • 1
    • ]. 

    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.

  • Provided by: [C].Flora of North America @
    • Source: [
    • 2
    • ]. 

    Decumbent or ascending glabrate aquatic perennials, the simple or branched, often fistulose stems to 100 cm. long. Leaves glabrous or glabrate, lanceolate to narrowly obovate, apically rounded to acute, basally cuneate, rarely denticulate, 2-10 cm. long, 0.5-2 cm. broad; petioles 1-3 mm. long. Inflorescences of terminal and occasionally axillary white glomes, 10-18 mm. long, 10-18 mm. broad, the usually unbranched peduncles 1-5 cm. long. Flowers perfect, bracts and bracteoles subequal, ovate, acuminate, 1-2 mm. long; sepals 5, subequal, oblong, apically acute and occasionally denticulate, neither indurate nor ribbed, 5-6 mm. long, 1.5-2.5 mm. broad; stamens 5, united below into a tube, the pseudostaminodia lacerate and exceeding the anthers; ovary reniform, the style about twice as long as the globose capitate stigma. Fruit an indehiscent reniform utricle 1 mm. long, 1-1.5 mm. broad; mature seeds not seen.

  • Provided by: [E].Flora de Panama
    • Source: [
    • 4
    • 3
    • ]. 

    "Stout perennial herb 3–10 dm, ascending or decumbent, villous at least in the axils; lvs subsessile, linear-elliptic to elliptic or obovate, 3.5–11 × 0.5–2 cm; peduncles axillary or terminal, simple, 1–5 cm, pilose; heads globose, 1.5 cm thick, white; bracts a fourth as long as the sep, broadly ovate, acute or acuminate, glabrous; sep ovate-oblong, 6 mm, acute or acutish, subchartaceous; staminodes surpassing the anthers; style elongate, the stigma entire. Wet places; native to tropical Amer., intr. as a weed in the coastal states from se. Va. to Fla. and Tex."

  • Provided by: [F].New York Botanical Garden
    • Source: [
    • 5
    • ]. 


    the range of this species as from Colombia to Brazil and Argentina, adventive in the southeastern United States.

  • Provided by: [E].Flora de Panama
    • Source: [
    • 4
    • 3
    • ]. 

    Distribution Map

    • Native distribution
    Found in
    • Southern America Brazil Amapí
    • Amazonas
    • Parí
    • Alagoas
    • Bahia
    • Paraába
    • Pernambuco
    • Rio Grande do Norte
    • Sergipe
    • Paraní
    • Rio Grande do Sul
    • Santa Catarina
    • Espirito Santo
    • Minas Gerais
    • São Paulo
    • Mato Grosso
    • Mato Grosso do Sul

    Other Local Names


     Information From

    World Flora Online Data. 2017.
    • A CC0 1.0 Universal (CC0 1.0).
    MBG Floras Images
    Flora images. Missouri Botanical Garden. Accessed on Jun. 2018.
    • B Missouri Botanical Garden
    Flora of North America @
    'Flora of North America @ eFloras (2008). Published on the Internet [accessed August 2016]' Missouri Botanical Garden, St. Louis, MO & Harvard University Herbaria, Cambridge, MA.
    • C Flora of North America Association
    Brazilian Flora 2020 project - Projeto Flora do Brasil 2020
    Brazil Flora G (2014): Brazilian Flora 2020 project - Projeto Flora do Brasil 2020. v393.147. Instituto de Pesquisas Jardim Botanico do Rio de Janeiro. Dataset/Checklist. doi:10.15468/1mtkaw
    • D Group Brazil Flora, REFLORA Program
    Flora de Panama
    Robert E. Woodson, Jr. and Robert W. Schery Annals of the Missouri Botanical Garden Vol. 67, No. 4 (1980), pp. ii-xxxiii
    • E Missouri Botanical Garden
    New York Botanical Garden
    Descriptions of plants should be attributed to the full citation for each individual article, chapter or book that is the source for each record, which should include the authors of original publication.
    • F Content licensed under Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License
    Flora Of CHina @
    'Flora of China @ eFloras (2008). Published on the Internet [accessed August 2016]' Missouri Botanical Garden, St. Louis, MO & Harvard University Herbaria, Cambridge, MA.
    • G Missouri Botanical Garden
    World Flora Online consortium
    World Flora Online Data. 2018.
    • H CC0 1.0 Universal (CC0 1.0).