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Argentine fleabane, asthmaweed, flax-leaf fleabane, flax-leaf horseweed, hairy horseweed, South American conyza, wavy-leaf fleabane

Habit Plants erect, 10–100(–150+) cm, branched mostly distally.

faces ± densely strigose or hispidulous;

proximal blades oblanceolate, 30–80(–120+) × 10–25+ mm, obscurely lobed to coarsely toothed or entire;

distal narrowly oblanceolate to linear, 10–50 × 2–10 mm, obscurely toothed or entire.


3.5–5 mm.


3–5 mm diam. in fruit.

Pistillate florets


corollas ± equaling or surpassing styles, laminae 0 or to 0.3 mm.

Disc florets



usually strigose or hispidulous;

outer greenish to purplish, lanceolate, shorter;

inner stramineous to purplish, linear-attenuate (more chartaceous to scarious, less hairy).


usually in paniculiform to racemiform, rarely corymbiform arrays.


pale tan, 1–1.5 mm, faces glabrous or sparsely strigillose;

pappi of 15–25+, pinkish, sordid, or tawny bristles 3–4+ mm.


= 54.

Conyza bonariensis

Phenology Flowering year round, mostly late summer–fall.
Habitat Disturbed sites, along roads and streets
Elevation 0–500 m (0–1600 ft)
from FNA
AL; AZ; CA; FL; GA; LA; MS; NC; NM; OR; SC; TX; UT; VA; South America [Introduced in North America]
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Conyza bonariensis is widespread in tropical and warm-temperate regions of the world. It is thought to be native to South America.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 20, p. 349.
Parent taxa Asteraceae > tribe Astereae > Conyza
Sibling taxa
C. canadensis, C. floribunda, C. ramosissima
Synonyms Erigeron bonariensis
Name authority (Linnaeus) Cronquist: Bull. Torrey Bot. Club 70: 632. (1943)
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