Ageratina jucunda
Ageratina thyrsiflora
hammock snakeroot, lesser snakeroot
congested snakeroot
erect, lax, minutely pilose.
erect (usually forming compact ‘bushlets’), finely and evenly puberulent (hairs minute, bent).
opposite;
petioles 7–15(–22) mm;
blades narrowly deltate to rhombic, 2–6(–7) × 1.5–4 cm, (usually subcoriaceous) bases usually cuneate, sometimes truncate to slightly subcordate, margins usually coarsely serrate or incised, sometimes crenate to subentire, apices acute to acuminate, abaxial faces glabrous or hairy on veins.
usually alternate, sometimes subopposite (densely overlapping internodes);
petioles 3–20 mm;
blades ovate-lanceolate to triangular, 2.5–6.5 × 1–2.5(–3) cm, bases obtuse to cuneate, margins shallowly and coarsely crenate to serrate to subentire, apices rounded-obtuse, abaxial faces hirtellous.
2–10 mm, sparsely puberulent.
3–8 mm, puberulent.
2.5–4 mm.
2.5–3 mm.
white, lobes glabrous or sparsely short-hirtellous.
white (orange-veined), glabrous.
apices acute, abaxial faces puberulent to villous-puberulent.
apices acute to obtuse (dark orange-veined), abaxial faces.
clustered.
clustered (in dense, terminal aggregates).
usually finely hirtellous-strigose on distal 1/3, sometimes glabrous.
hispid.
= 34.
Ageratina jucunda
Ageratina thyrsiflora
Ageratina thyrsiflora is known from the United States from a single collection dated 1929 from “near Nogales” in Santa Cruz County. It is recognized by its strict, unbranched or few-branched stems with alternate, densely arranged leaves, relatively small heads densely clustered in terminal aggregates, orange-veined phyllaries and corollas, and closely puberulent stems and petioles (hairs minute, sharply upwardly bent).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
WildflowerSearch
iNaturalist
USDA Plants Database
