Erigeron filifolius |
Erigeron compositus |
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Peck's threadleaf fleabane, thread-leaf daisy, thread-leaf 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, 10–30(–50) cm; taprooted, caudices multicipital, often with relatively short and thin, stemlike, lignescent branches. | 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, sparsely to densely strigose (hairs loosely appressed to ascending, fine), densely white-strigose at least proximally, eglandular. |
erect (simple, ± scapiform), sparsely hispido-pilose, minutely glandular. |
Leaves | basal (usually persistent, not clustered as rosettes) and cauline; basal blades linear to filiform, 10–80 × 0.5–2.5(–3.5) mm; cauline gradually or little reduced distally, margins entire, faces sparsely to moderately strigose, eglandular. |
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 | 4–7 × 5–-18 mm. |
5–10 × 8–20 mm. |
Ray florets | (15–)20–125; corollas usually blue, sometimes white, pink, or pale lavender, 3–13 mm, laminae coiling. |
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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 | 2.5–5.5 mm. |
3–5 mm. |
Phyllaries | in (2–)3–4 series, loosely strigose to hirsute or nearly villous, densely to sparsely minutely glandular. |
in 2–3 series (purple-tipped), hirsute (hairs spreading), minutely glandular. |
Heads | 1–5(–10+) from distal branches, tending to be in corymbiform arrays. |
(sometimes disciform) 1. |
Cypselae | 1.4–1.8(–2) mm, 2-nerved, faces sparsely strigose to glabrate; pappi: outer of setae, inner of 20–30 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. |
= 18, 36, 45, 54. |
Erigeron filifolius |
Erigeron compositus |
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Phenology | Flowering May–Aug. | Flowering (May–)Jun–Aug. |
Habitat | Dry, rocky or sandy soil, lava beds, bitterbrush, sagebrush, juniper, ponderosa pine | Sagebrush, rabbitbrush, aspen to aspen-fir, subalpine meadows, cliffs, talus, and boulders |
Elevation | 400–2400 m (1300–7900 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 |
CA; ID; MT; NV; OR; UT; WA; BC
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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 | The densely white-strigose stem bases, linear-filiform leaves relatively unreduced distally, and relatively few heads with coiling, usually blue rays are distinctive for Erigeron filifolius. Proximal leaves are not clustered as a basal rosette; they are inserted on closely spaced nodes that are slightly more separated distally. Plants identified as var. robustior (with more ray florets, fewer heads, and thicker stems, centered in Oregon and Washington) intergrade with the typical form and apparently are separated arbitrarily. (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. 298. | FNA vol. 20, p. 300. |
Parent taxa | Asteraceae > tribe Astereae > Erigeron | Asteraceae > tribe Astereae > Erigeron |
Sibling taxa | ||
Synonyms | Diplopappus filifolius, E. filifolius var. robustior | E. compositus var. discoideus, E. compositus var. glabratus, E. compositus var. multifidus, E. gormanii |
Name authority | (Hooker) Nuttall: Trans. Amer. Philos. Soc., n. s. 7: 308. (1840) | Pursh: Fl. Amer. Sept. 2: 535. (1813) |
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