Erigeron filifolius |
Erigeron denalii |
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Peck's threadleaf fleabane, thread-leaf daisy, thread-leaf fleabane |
Denali fleabane |
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Habit | Perennials, 10–30(–50) cm; taprooted, caudices multicipital, often with relatively short and thin, stemlike, lignescent branches. | Perennials, 1–5 cm; taprooted, caudices diffuse with extensive systems of rhizomelike, relatively long and slender branches. |
Stems | erect, sparsely to densely strigose (hairs loosely appressed to ascending, fine), densely white-strigose at least proximally, eglandular. |
erect (simple, ± scapiform), villous, granular-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. |
basal (persistent) and cauline; blades spatulate to oblanceolate-spatulate, 10–20 × 2–4(–5) mm, mid larger than basal and proximal, margins entire or shallowly (2–)3-lobed or -toothed apically (apices obtuse to nearly truncate), faces moderately villous, minutely glandular. |
Involucres | 4–7 × 5–-18 mm. |
(4–)5–7 × 9–12 mm. |
Ray florets | (15–)20–125; corollas usually blue, sometimes white, pink, or pale lavender, 3–13 mm, laminae coiling. |
30–55; corollas white to lavender, 4–8 mm, laminae (filiform to narrowly straplike, 0.3–2 mm wide, often involute) erect, rarely spreading, not coiling or reflexing. |
Disc florets/ |
2.5–5.5 mm. |
3.8–4.8 mm. |
Phyllaries | in (2–)3–4 series, loosely strigose to hirsute or nearly villous, densely to sparsely minutely glandular. |
in 2(–3) series, densely lanate-villous (hairs to 3 mm, often with dark purple cross walls), glandular. |
Heads | 1–5(–10+) from distal branches, tending to be in corymbiform arrays. |
1. |
Cypselae | 1.4–1.8(–2) mm, 2-nerved, faces sparsely strigose to glabrate; pappi: outer of setae, inner of 20–30 bristles. |
3–3.8 mm, 2-nerved, faces strigillose to strigoso-hirsute; pappi: outer 0 (or inconspicuous), inner of 20–25 (usually ± purple-red tinged, sometimes whitish, variable within populations) bristles. |
2n | = 18. |
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Erigeron filifolius |
Erigeron denalii |
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Phenology | Flowering May–Aug. | Flowering Jun–Aug. |
Habitat | Dry, rocky or sandy soil, lava beds, bitterbrush, sagebrush, juniper, ponderosa pine | Open alpine and subalpine habitats, tundra slopes, openings in spruce-fir woods, gravelly and shaley scree, cut banks |
Elevation | 400–2400 m (1300–7900 ft) | 900–2200 m (3000–7200 ft) |
Distribution |
CA; ID; MT; NV; OR; UT; WA; BC
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AK; NT; YT; BC |
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.) |
Erigeron denalii and E. purpuratus are similar and probably closely related; the two appear to be partially sympatric; differences in vestiture and leaf morphology are constant. The habitat of E. purpuratus, sandy or gravelly alluvium, also is remarkably constant and distinct from that of E. denalii. Apparently correlated with the habitat, plants of E. purpuratus almost always develop a relatively long and slender, woody taproot; taproots of E. denalii apparently are less well defined and often are not collected. Plants of the type collection of Erigeron mexiae have ray corollas with relatively broad laminae (1.5–2 mm wide); ray corolla width is variable in E. denalii, and E. mexiae is regarded here as an extreme variant within the species. In other characters, there appears to be no difference. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 20, p. 298. | FNA vol. 20, p. 303. |
Parent taxa | Asteraceae > tribe Astereae > Erigeron | Asteraceae > tribe Astereae > Erigeron |
Sibling taxa | ||
Synonyms | Diplopappus filifolius, E. filifolius var. robustior | E. mexiae, E. purpuratus var. dilatatus |
Name authority | (Hooker) Nuttall: Trans. Amer. Philos. Soc., n. s. 7: 308. (1840) | A. Nelson: Amer. J. Bot. 32: 289. (1945) |
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