Ageratina lemmonii

Perennials, 20-40(-70) cm (densely fibrous-rooted crowns). Stems (commonly purple) erect, puberulous (hairs usually with colored crosswalls). Leaves opposite; petioles usually 0, sometimes 1-2 mm; blades ovate-lanceolate, 2-4.5 × 0.5-2.5 cm, margins shallowly serrate, abaxial faces glabrous or glabrate, gland-dotted. Heads in loose, open arrays. Peduncles 10-60 mm, puberulent. Involucres 4-5.5 mm. Phyllaries: (narrowly oblong-lanceolate) apices acute, abaxial faces sparsely hairy to glabrate. Corollas white, lobes densely hispid-villous. Cypselae sparsely and finely hispidulous. 2n = 34.

Flowering Aug-Oct. Rocky slopes, mostly in pine-oak woodlands; 1800-2800[-3300, Mexico] m; Ariz.; Mexico.