Erigeron leiomerus A. Gray

Perennials, 4–12(–15) cm; taprooted (taproots often not evident or not collected), caudices with diffuse system of relatively long and slender, rhizomelike branches. Stems decumbent to ascending or erect (usually purplish proximally, sometimes greenish), glabrous or sparsely strigillose (hairs closely to loosely appressed), eglandular. Leaves basal and cauline; basal blades oblanceolate to obovate or spatulate, 15–70 × 2–11(–15) mm, cauline reduced distally (bases of basal sometimes purplish, enlarged; of cauline, not sub-clasping), margins entire, faces glabrous or sparsely strigose, eglandular. Heads 1. Involucres 4–6 × 7–13 mm. Phyllaries in 2–3 series (often purplish, narrowly elliptic, erect, apices appressed), glabrous or sparsely strigose, minutely glandular. Ray florets 15–60; corollas white to blue or purple, 6–11 mm, laminae reflexing. Disc corollas 3.2–4.4 mm. Cypselae 2–2.2 mm, 2-nerved, faces sparsely strigose; pappi: outer of setae, inner of 15–25 bristles. 2n = 18.

Erigeron leiomerus is a rare species of flowering plant in the family Asteraceae known by the common names rockslide yellow fleabane or rockslide fleabane. It is native to the western United States, primarily in the Rocky Mountains and the Great Basin. It has been found in Montana, Idaho, Nevada, Utah, Wyoming, Colorado, and New Mexico.

Erigeron leiomerus is a branching perennial herb up to 15 centimeters (6 inches) tall, producing a woody taproot. The leaves and the stem are covered with hairs. The plant generally produces only 1 flower head per stem, each head with up to 60 purple, blue, white ray florets surrounding numerous yellow disc florets. The species grows on rockslides in alpine tundra and coniferous forests at high elevations.

Erigeron leiomerus là một loài thực vật có hoa trong họ Cúc. Loài này được A.Gray mô tả khoa học đầu tiên năm 1884.