Erigeron engelmannii |
Erigeron compositus |
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Engelmann's fleabane |
cut-leaf daisy, cut-leaf fleabane, dwarf mountain fleabane, fern-leaf fleabane, trifid mountain fleabane, vergerette à feuilles segmentées |
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Habit | Perennials, 3–20(–30) cm; taprooted, caudex branches relatively short and thick. | 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, loosely to closely, sparsely to moderately strigose (hairs 0.1–0.9 mm), usually minutely glandular (glands barely evident), sometimes eglandular. |
erect (simple, ± scapiform), sparsely hispido-pilose, minutely glandular. |
Leaves | basal (usually persistent) and cauline (petioles prominently ciliate at least on proximal portions, hairs spreading, thick-based); basal blades linear-oblanceolate, 20–100 × 1–4 mm, margins entire, faces strigose, eglandular; cauline usually restricted to proximal 1/2 of stems, slightly reduced distally. |
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. |
Involucres | 3.5–5(–6) × 7–12 mm. |
5–10 × 8–20 mm. |
Ray florets | (35–)45–100; corollas white, sometimes pink or bluish, 5–10 mm, laminae (0.8–1.1 mm wide) primarily reflexing, sometimes also weakly coiling at the tips. |
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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. |
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Disc corollas | (2.5–)2.7–4.2 mm (throats indurate and inflated, densely puberulent). |
3–5 mm. |
Phyllaries | in 2–3(–4) series, coarsely hirsuto-villous, sparsely to moderately minutely glandular. |
in 2–3 series (purple-tipped), hirsute (hairs spreading), minutely glandular. |
Heads | 1(–3). |
(sometimes disciform) 1. |
Cypselae | 1.4–1.8 mm (oblong), 2-nerved, faces sparsely strigose; pappi: outer usually of narrow scales, sometimes 0 or of setae, inner of 12–20 bristles. |
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. |
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Erigeron engelmannii |
Erigeron compositus |
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Phenology | Flowering (Apr–)May–Jul. | Flowering (May–)Jun–Aug. |
Habitat | Dry, sandy or rocky sites, prairies, often with sagebrush, rabbitbrush, juniper, pinyon-juniper, salt desert shrub | Sagebrush, rabbitbrush, aspen to aspen-fir, subalpine meadows, cliffs, talus, and boulders |
Elevation | 1300–2500 m (4300–8200 ft) | (in e Canada, possibly Greenland and Arctic bridge gap, 10–200–)1800–4300 m ((in e Canada, possibly Greenland and Arctic bridge gap, 0–700–)5900–14100 ft) |
Distribution |
CO; ID; UT; WY
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AK; AZ; CA; CO; ID; MT; ND; NV; OR; SD; UT; WA; WY; AB; BC; NF; NT; NU; QC; SK; YT; Greenland; e Asia (Russian Far East)
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Discussion | Plants from Chaffee and Fremont counties, Colorado, have strigose leaves and the compact habit of Erigeron engelmannii but sparsely spreading-hirsute stems; they may be intermediate between E. engelmannii and E. concinnus. Unusual variation in the pappi of E. engelmannii also suggests that the species needs study and better definition. A. Cronquist observed that “Erigeron engelmannii intergrades completely with E. pumilus, yet has two geographic subspecies of its own, and shows no distributional similarity to the [taxa] of E. pumilus,” and that E. engelmannii is “smaller and more delicate, with shorter finer hairs, and [has] smaller heads with usually fewer ligules.” (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 20, p. 290. | FNA vol. 20, p. 300. |
Parent taxa | Asteraceae > tribe Astereae > Erigeron | Asteraceae > tribe Astereae > Erigeron |
Sibling taxa | ||
Synonyms | E. compositus var. discoideus, E. compositus var. glabratus, E. compositus var. multifidus, E. gormanii | |
Name authority | A. Nelson: Bull. Torrey Bot. Club 26: 247. (1899) | Pursh: Fl. Amer. Sept. 2: 535. (1813) |
Web links |