Ageratina adenophora

(Sprengel) R. M. King & H. Robinson

Phytologia 19: 211. 1970

Common names: Crofton weed sticky snakeroot
Basionyms: Eupatorium adenophorum Sprengel
Treatment appears in FNA Volume 21. Treatment on page 553. Mentioned on page 547, 548.
Subshrubs, 50–220 cm. Stems (usually purplish when young) erect, stipitate-glandular. Leaves opposite; petioles 10–25 mm; blades (abaxially purple) ovate-lanceolate or ovate-deltate to lanceolate-ovate, (1.5–)2.5–5.5(–8) × 1.5–4(–6) cm, bases cuneate to obtuse or nearly truncate, margins serrate, apices acute to acuminate, abaxial faces stipitate- to sessile-glandular. Heads clustered. Peduncles 5–12 mm, densely stipitate-glandular and sometimes also sparsely viscid-puberulent. Involucres 3.5–4 mm. Phyllaries: apices acute, abaxial faces stipitate-glandular. Corollas white, pink-tinged, lobes sparsely hispidulous. Cypselae glabrous. 2n = 51.

Phenology: Flowering Mar–Aug(–Sep).
Habitat: Stream margins, ditches, road embankments, hillsides
Elevation: 400–900 m



Intoduced, Calif., Mexico, also introduced in Europe, Pacific Islands (New Zealand).




Lower Taxa

No lower taxa listed.