Erigeron filifolius |
Erigeron radicatus |
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Peck's threadleaf fleabane, thread-leaf daisy, thread-leaf fleabane |
Hooker's fleabane, Huber's fleabane, tap-root 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–)2–6(–12) cm; taprooted, caudices branches relatively short, thick. |
Stems | erect, sparsely to densely strigose (hairs loosely appressed to ascending, fine), densely white-strigose at least proximally, eglandular. |
erect, strigose to sparsely or densely short-villous (hairs loosely appressed to ascending or spreading), eglandular. |
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) (eciliate or weakly ciliate proximally); blades 1-nerved linear to narrowly oblanceolate or subspatulate, (5–)10–50(–60) × 0.8–2.5 mm (bases gradually narrowing), margins entire (apices obtuse to rounded), abaxial faces glabrate or glabrous, shiny, adaxial sparsely, loosely strigose, eglandular; cauline mostly on proximal 1/2–1/3 of stems (absent in some high elevation forms), abruptly or gradually reduced distally. |
Involucres | 4–7 × 5–-18 mm. |
(3–)4–6(–8) × (5–)8–12(–15) mm. |
Ray florets | (15–)20–125; corollas usually blue, sometimes white, pink, or pale lavender, 3–13 mm, laminae coiling. |
(12–)20–44(–85); corollas white, less commonly purplish, 4–7(–8) mm, laminae coiling. |
Disc corollas | 2.5–5.5 mm. |
(2–)2.5–3.5(–4) mm. |
Phyllaries | in (2–)3–4 series, loosely strigose to hirsute or nearly villous, densely to sparsely minutely glandular. |
in 2–3(–4) series (subequal), villosulous to villoso-hirsutulous (hairs usually with purplish cross walls at least in basal cells), minutely glandular apically or eglandular. |
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. |
2.1–2.5 mm, 2-nerved, faces sparsely strigose; pappi: outer of scales, inner of (6–)7–11 (readily falling) bristles. |
2n | = 18. |
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Erigeron filifolius |
Erigeron radicatus |
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Phenology | Flowering May–Aug. | Flowering May–Aug. |
Habitat | Dry, rocky or sandy soil, lava beds, bitterbrush, sagebrush, juniper, ponderosa pine | Rocky slopes, ridges, and summits, ledges and crevices, outcrops and talus, usually limestone, alpine tundra |
Elevation | 400–2400 m (1300–7900 ft) | (1400–)1600–2800(–3400) m ((4600–)5200–9200(–11200) ft) |
Distribution |
CA; ID; MT; NV; OR; UT; WA; BC
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CO; ID; MT; ND; NE; SD; UT; WY; AB; SK
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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.) |
Collections of Erigeron radicatus often have been identified as E. ochroleucus var. scribneri; E. radicatus is distinctive in its branched caudex, villous cauline vestiture, more reduced leaf vestiture, involucral vestiture of hairs with purple cross walls, shorter disc corollas, and relatively few, readily falling pappus bristles. Erigeron radicatus often is essentially scapiform at relatively high elevation (2700–3400 m) in Idaho, Montana, Utah, and Wyoming; more eastern populations in the Great Plains, at lower elevations (1400–2600 m), have leafier stems but are hardly different in other features. Plants of some populations in Albany and Carbon counties, Wyoming, produce atypically shorter rays. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 20, p. 298. | FNA vol. 20, p. 294. |
Parent taxa | Asteraceae > tribe Astereae > Erigeron | Asteraceae > tribe Astereae > Erigeron |
Sibling taxa | ||
Synonyms | Diplopappus filifolius, E. filifolius var. robustior | E. huberi, E. macounii |
Name authority | (Hooker) Nuttall: Trans. Amer. Philos. Soc., n. s. 7: 308. (1840) | Hooker: Fl. Bor.-Amer. 2: 17, plate 122. (1834) |
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