Erigeron filifolius |
Erigeron divergens |
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Peck's threadleaf fleabane, thread-leaf daisy, thread-leaf fleabane |
branching fleabane diffuse daisy, diffuse daisy, diffuse fleabane, spreading fleabane |
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Habit | Perennials, 10–30(–50) cm; taprooted, caudices multicipital, often with relatively short and thin, stemlike, lignescent branches. | Annuals or short-lived perennials, (7–)12–40(–70) cm; taprooted, caudices simple if perennial. |
Stems | erect, sparsely to densely strigose (hairs loosely appressed to ascending, fine), densely white-strigose at least proximally, eglandular. |
(single or multiple from bases) erect to ascending, densely and evenly puberulous-hirsutulous (hairs spreading to spreading-descending or -ascending, often crinkly, bases not thickened), minutely glandular at least distally, usually throughout. |
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 (usually deciduous) and cauline; basal blades obovate-spatulate, 10–70 × 4–-14 mm; cauline gradually reduced distally, margins entire or with 2–3 pairs of teeth or lobes, faces hirsute to loosely strigoso-hirsute, sometimes sparsely glandular. |
Involucres | 4–7 × 5–-18 mm. |
3–4 × (5–)7–11 mm. |
Ray florets | (15–)20–125; corollas usually blue, sometimes white, pink, or pale lavender, 3–13 mm, laminae coiling. |
75–150; corollas white, drying lilac, without abaxial midstripe, (2–)4–9.5 mm, laminae not coiling or reflexing (remaining relatively straight). |
Disc corollas | 2.5–5.5 mm. |
1.8–2.3 mm (throats indurate and slightly inflated). |
Phyllaries | in (2–)3–4 series, loosely strigose to hirsute or nearly villous, densely to sparsely minutely glandular. |
in 3–4 series, hirsute, minutely glandular. |
Heads | 1–5(–10+) from distal branches, tending to be in corymbiform arrays. |
(in early season, 1–)5–100+ (buds nodding). |
Cypselae | 1.4–1.8(–2) mm, 2-nerved, faces sparsely strigose to glabrate; pappi: outer of setae, inner of 20–30 bristles. |
0.9–1.2 mm, 2-nerved (nerves whitish), faces sparsely strigose; pappi: outer of setae or scales, inner of 6–9(–12) bristles. |
2n | = 18. |
= 18, 27, 36. |
Erigeron filifolius |
Erigeron divergens |
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Phenology | Flowering May–Aug. | Flowering (Feb–)Apr–Oct. |
Habitat | Dry, rocky or sandy soil, lava beds, bitterbrush, sagebrush, juniper, ponderosa pine | Gravelly or sandy flats, riverbanks, meadows, disturbed sites, desert scrubland to grasslands, saltbush, blackbrush, sagebrush, pinyon-juniper, juniper-oak, oak, and ponderosa pine woodlands |
Elevation | 400–2400 m (1300–7900 ft) | 60–2000(–2700) m (200–6600(–8900) ft) |
Distribution |
CA; ID; MT; NV; OR; UT; WA; BC
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AZ; CA; CO; ID; MT; ND; NE; NM; NV; OK; OR; SD; TX; UT; WA; WY; AB; BC; Mexico (Baja California, Chihuahua, Coahuila, Durango, Sonora, and southward)
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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.) |
Polyploidy and agamospermy apparently are common in Erigeron divergens and contribute to the variability and, probably to some extent, the polymorphism characteristic of this species. Diploids appear to be scattered through the range of the species, at least in its southern part. The form of Erigeron divergens with persistent, deeply pinnatifid basal leaves with relatively long petioles and tendency toward perenniality (woody taproots) has been named E. accedens [occurs at 200–1000(–1200) m and flowers Feb–Apr(–May)]. Such plants have sometimes been identified as E. lobatus, and it is possible that they may have originated as hybrids with it; in most ways they are similar to E. divergens and apparently intergrade with it. The E. accedens form occurs in California, Arizona, New Mexico, southwest Texas, Baja California, northern Sonora, Durango, and Chihuahua, apparently sympatrically with more typical E. divergens, suggesting that the former is stabilized and self-reproductive (probably agamospermic). Available chromosome counts are triploid. Rare plants (e.g., E. incomptus) may have filiform rays barely extending past the involucre. Another common form of Erigeron divergens in the broad sense (mostly in Chihuahua, also southern Texas, New Mexico, and Arizona) has bowl-shaped plants with decumbent stems, a discrete taproot, persistent, lobed basal leaves, and solitary heads topping usually simple stems, and usually is early-season in phenology. Further comments related to variation in E. divergens are found under 163. Erigeron multiceps. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 20, p. 298. | FNA vol. 20, p. 339. |
Parent taxa | Asteraceae > tribe Astereae > Erigeron | Asteraceae > tribe Astereae > Erigeron |
Sibling taxa | ||
Synonyms | Diplopappus filifolius, E. filifolius var. robustior | E. divaricatus, E. accedens, E. incomptus, E. solisaltator |
Name authority | (Hooker) Nuttall: Trans. Amer. Philos. Soc., n. s. 7: 308. (1840) | Torrey & A. Gray: Fl. N. Amer. 2: 175. (1841) |
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