Blackhead Fleabane

Perennials, 3–12(–21 at lower elevations) cm; fibrous-rooted, rhizomatous, caudices decumbent, often branched, rhizomelike, sometimes taprootlike. Stems erect, distally villous (hairs with black cross walls), minutely glandular near heads. Leaves mostly basal (persistent), some cauline; blades spatulate to oblanceolate, (10–)20–50(–150) × 4–6(–15) mm, cauline linear, bractlike, margins entire (apices rounded to retuse), faces glabrous or sparsely hirsute, eglandular. Heads 1. Involucres 6–9 × 10–14 mm. Phyllaries in 2(–3) series, sparsely villoso-sericeous (hairs flattened, cross walls black, imparting distinct black color to involucres), glandular. Ray florets 45–74; corollas white to purple, 7–11 mm (mostly 1–2 mm wide), laminae spreading, tardily coiling. Disc corollas 2.4–3.2 mm. Cypselae (oblanceoloid-oblong) 2–2.3 mm, 2-nerved, faces strigoso-hirsute; pappi: outer of setae, inner of 15–30 bristles. 2n = 18.

Erigeron uniflorus Linnaeus var. melanocephalus A. Nelson, Wyoming Agric. Exp. Sta. Bull. 28: 131. 1896

Erigeron melanocephalus is a North American species of flowering plant in the family Asteraceae known by the common name black-headed fleabane. It is found in the Rocky Mountains of the western United States, in the states of Wyoming, Colorado, New Mexico, and Utah.

Erigeron melanocephalus is a perennial herb up to 21 centimeters (8.4 inches) tall, spreading by means of underground rhizomes. The leaves are mostly crowded around the base of the stem. The plant generally produces only 1 flower heads per stem, each head with black hairs covering the phyllaries (bracts) covering the base of the head (hence the name black-headed fleabane). Each head also has up to 74 white or purple ray florets surrounding numerous yellow disc florets.