Cutleaf Daisy

Correlations among ploidal level, breeding systems, and morphologic variation have been studied in detail in Erigeron compositus. Five informally designated population systems of diploids are geographically restricted (all of the northwestern United States and adjacent Canada) and primarily sexual, compared to the polyploids, which are agamospermous and apparently of hybrid origin, at least in some cases (R. D. Noyes et al. 1995; Noyes and D. E. Soltis 1996). Reduction in ray floret laminae usually is correlated with polyploidy. Plants with 1-ternately lobed leaves have been identified as var. glabratus, an element of variation that does not have a geographic pattern.

Among closely related species, Erigeron compositus is the only one that produces strongly thickened caudex branches; occasional collections show a tendency toward the slender, loose branches characteristic of the other species.

Perennials, 5–15(–25 cm); taprooted, caudices simple or branches usually relatively thick and short, rarely slender and rhizomelike, covered with persistent leaf bases. Stems erect (simple, ± scapiform), sparsely hispido-pilose, minutely glandular. Leaves mostly basal (persistent); blades spatulate to obovate-spatulate, 5–50(–70) × (2–)4–12 mm, margins (1–)2–3(–4)-ternately lobed or dissected, cauline bractlike, mostly entire, faces densely hispiduloso-puberulent to glabrate, minutely glandular. Heads (sometimes disciform) 1. Involucres 5–10 × 8–20 mm. Phyllaries in 2–3 series (purple-tipped), hirsute (hairs spreading), minutely glandular. Ray (pistillate) florets 20–60; corollas white to pink or blue, usually 6–12 mm, often reduced to tubes (heads disciform), laminae not coiling or reflexing. Disc corollas 3–5 mm. Cypselae 1.6–2.7 mm, 2-nerved, faces sparsely strigose-hirsute; pappi: outer usually of setae, sometimes 0, inner of 12–20 bristles. 2n = 18, 36, 45, 54.

Erigeron compositus var. discoideus A. Gray; E. compositus var. glabratus Macoun; E. compositus var. multifidus (Rydberg) J. F. Macbride & Payson; E. gormanii Greene

Erigeron compositus is an Arctic and alpine species of fleabane in the family Asteraceae. Common names include dwarf mountain fleabane, cutleaf daisy, and trifid mountain fleabane.

Erigeron compositus has been found in the Russian Far East (Wrangel Island and Chukotka), Alaska, Greenland, much of Canada (all three Arctic territories plus British Columbia, all three Prairie Provinces, Quebec, Newfoundland, and Nova Scotia), and the Western United States (from the Pacific Coast as far east as the Dakotas, Colorado, and New Mexico).

Erigeron compositus is perennial herb rarely more than 25 cm (10 in) tall, with a thick growth of basal leaves, the tips of which are divided. The plant produces a taproot and spreads by means of horizontal underground rhizomes. There is generally only one flower head per stem, each head with 20–60 white, pink or blue ray florets; these are sometimes small and easily mistaken for disc florets. Genuine disc florets are yellow and in the center of the head.