Print Fact SheetAgeratum conyzoides

Taxonomy

Ageratum conyzoides L., Sp. Pl. 2:839. 1753.

Common synonyms

Ageratum album Hort.Berol.; Ageratum album Hort.Berol. ex Hornem.; Ageratum album sp. steudel; Ageratum arsenei B.L.Rob.; Ageratum brachystephanum Regel; Ageratum ciliare L.; Ageratum ciliare Lour.; Ageratum coeruleum Desf.; Ageratum conyzoides f. album (Willd.) B.L.Rob.; Ageratum conyzoides f. conyzoides; Ageratum conyzoides f. obtusifolia (Lam.) Miq.; Ageratum conyzoides var. hirtum (Lam.) DC.; Ageratum conyzoides var. inaequipaleaceum Hieron.; Ageratum conyzoides var. obtusifolium (Lam.) DC.; Ageratum conyzoides var. pilosum Blume; Ageratum cordifolium Roxb.; Ageratum hirsutum Lam.; Ageratum hirsutum Poiret; Ageratum hirtum Lam.; Ageratum humile Larrañaga; Ageratum humile Salisb.; Ageratum iltisii R.M.King & H.Rob.; Ageratum latifolium var. galapageium B.L.Rob.; Ageratum latifolium var. latifolium; Ageratum microcarpum (Benth. ex Benth.) Hemsl.; Ageratum muticum Griseb.; Ageratum nanum; Ageratum nanum Hort. ex Sch.Bip.; Ageratum obtusifolium Lam.; Ageratum odoratum Bailly; Ageratum odoratum Vilm.; Ageratum suffruticosum Regel; Alomia microcarpa f. torresii Standl.; Cacalia mentrasto Vell. Conc.; Caelestina latifolia Benth. ex Oersted; Caelestina microcarpa Benth. ex Benth.; Caelestina microcarpa Benth. ex Oerst.; Caelestina suffruticosa Sweet; Carelia brachystephana (Regel) Kuntze; Carelia conyzoides (L.) Kuntze; Carelia conyzoides var. alba Kuntze; Carelia conyzoides var. coerulea Kuntze; Carelia conyzoides var. robusta Kuntze; Carelia mutica (Griseb.) Kuntze; Coelestina microcarpa Benth. ex Benth.; Coelestina microcarpa Benth. ex Oerst.; Coelestina suffruticosa Sweet; Eupatorium conyzoides (L.) E. H. Krause; Eupatorium paleaceum Sessé & Moc.; Sparganophorus obtusifolius Lag.

Common name

Billygoat weed/plant, ageratum, chickweed, goatweed

Description

Propagule or dispersal unit is the fruit with pappus. Fertile part 1.2-2.2 mm long, 0.2-0.5 mm wide, in side view widest in upper part (obovoid), rarely mostly +/- equal thickness (cylindrical), +/- straight or conspicuously curved, the upper (apical) end narrowing or suddenly cut off (truncate), in cross-section angular (prismatic), rarely flattened, basal scar (carpopodium) pronounced and well-differentiated, central or off to the side (oblique) or at least asymmetric, beak (=thinner sterile stalk between seed and pappus) absent, wings absent, fruit surface black, smooth (except at cellular level), with no hairs (glabrous) or simple straight hairs, thickened margin absent, longitudinal ribs present, 5, their surfaces smooth, with simple straight hairs, rarely no hairs (glabrous).

Pappus type wide flattened bristles / hairs or long slender scales, pappus elements all +/- similar, up to 1.6-3 mm long, in one row, number of pappus elements five or rarely a few more, persistent, the individual bristles rough / serrated (barbellate), clearly wider at base, white / translucent or brown.

Ecology

Annual herb, fruits wind-dispersed. Tropical to warm-temperate regions. Found in croplands, overgrazed pastures, disturbed forests and woodlands, grasslands and along creeks and rivers.

Native range

Central and tropical South America, Caribbean

Introduced range

Hawai'i, temperate Brazil, tropical and south-eastern Africa, Madagascar, tropical southern Asia (e.g. India, China, S Japan, Taiwan, Thailand, Phillipines, Indonesia, Papua New Guinea), Australia