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Ageratina thyrsiflora
(Greene) R.M. King & H. Rob.
Family:
Asteraceae
Congested Snakeroot
Sue Carnahan
FNA
Resources
Guy L. Nesom in Flora of North America (vol. 21)
Perennials or subshrubs,
50-100 cm.
Stems
erect (usually forming compact `bushlets´), finely and evenly puberulent (hairs minute, bent).
Leaves
usually alternate, sometimes subopposite (densely overlapping internodes); petioles 3-20 mm; blades ovate-lanceolate to triangular, 2.5-6.5 Ă— 1-2.5(-3) cm, bases obtuse to cuneate, margins shallowly and coarsely crenate to serrate to subentire, apices rounded-obtuse, abaxial faces hirtellous.
Heads
clustered (in dense, terminal aggregates).
Peduncles
3-8 mm, puberulent.
Involucres
2.5-3 mm.
Phyllaries:
apices acute to obtuse (dark orange-veined), abaxial faces.
Corollas
white (orange-veined), glabrous.
Cypselae
hispid.
Flowering Sep-Nov. Rocky sites, oak woodland; 1000-2200 m; Ariz.; Mexico (Chihuahua, Durango, Jalisco, Sinaloa, Sonora).
Open Interactive Map
Sue Carnahan
Sue Carnahan
Sue Carnahan
Sue Carnahan
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