Conyza bonariensis (L.) Cronquist

  • Authority

    Acevedo-Rodríguez, Pedro & collaborators. 1996. Flora of St. John, U.S. Virgin Islands. Mem. New York Bot. Gard. 78: 1-581.

  • Family

    Asteraceae

  • Scientific Name

    Conyza bonariensis (L.) Cronquist

  • Description

    Species Description - Annual pubescent herb 1-2 m tall; stems simple or branching in the inflorescence. Leaves cauline, numerous, tapering to a petiole-like base; blades 4-15 x 0.2-2 cm, oblanceolate to linearlanceolate, gradually reduced above, chartaceous, indistinctly 3- nerved from well above base, pubescent on both surfaces, eglandular, the margins entire or nearly so to less commonly deeply serrate. Inflorescence an open bracteate pyramidal panicle in the upper half of the plant. Heads to 200- or more flowered, to 6-7 mm tall and broad; involucre hemispheric, 4-6 mm tall, 2-3- seriate; involucral bracts narrowly lanceolate, 2.2-6 x 0.5-0.7 mm, hispid, eventually completely reflexed; receptacle flat to subconvex, to ca. 2 mm broad; peduncles 3-20 mm long, hispid, bracteolate. Outer flowers with corollas weakly zygomorphic, 3.5- 4.5 mm long, tubular, white or purplish at top, topped by a 0.3- 0.6 mm long inconspicuous limb. Inner flowers ca. 7-20(-30), filiform-cylindrical, ca. 3.5-4.5 mm long, shortly 5-lobed, yellowish. Achenes elliptic-oblong, 1.5-1.8 mm long, weakly puberulent; pappus of many bristles, 3-4 mm long.

  • Discussion

    Erigeron linifolius Willd., Sp. PI. 3: 1955. 1804. Leptilon linifolium (Willd.) Small, Fl. S.E. U.S. 1231, 1340. 1903

    Common name: hairy horseweed.

  • Distribution

    An occasional weed of open disturbed areas such as roadsides. Along road to Bordeaux (A2882, A3135), Susannaberg (A852). Also on St. Thomas and Tortola; throughout much of the West Indies, neotropics, and warmer parts of nontropical America. Introduced into the paleotropics.

    Saint Thomas Virgin Islands of the United States South America| Tortola Virgin Islands South America| West Indies|