Erigeron rydbergii |
Erigeron divergens |
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Rydberg's fleabane |
branching fleabane diffuse daisy, diffuse daisy, diffuse fleabane, spreading fleabane |
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Habit | Perennials, 2.5–6 cm; taprooted, caudex branches relatively short, thick. | Annuals or short-lived perennials, (7–)12–40(–70) cm; taprooted, caudices simple if perennial. |
Stems | erect, finely hirsutulous to villosulous, 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 | mostly basal (persistent); blades linear-oblanceolate to narrowly spatulate, 10–50 × 1–3 mm, cauline mostly on proximal 1/2 of stems, reduced distally, margins entire (apices obtuse to rounded), abaxial faces glabrous, adaxial glabrous or sparsely villous, 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 | 5–6 × 7–12 mm. |
3–4 × (5–)7–11 mm. |
Ray florets | 15–35; corollas usually bluish to purplish, rarely white, 6–9 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 | 3.7–5 mm. |
1.8–2.3 mm (throats indurate and slightly inflated). |
Phyllaries | in 2–3 series, densely and finely hirsuto-villous (hairs without colored cross walls), minutely and inconspicuously glandular. |
in 3–4 series, hirsute, minutely glandular. |
Heads | 1. |
(in early season, 1–)5–100+ (buds nodding). |
Cypselae | 1.8–2 mm, 2-nerved, faces sparsely strigose; pappi: outer of setae, inner of 15–20 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, 27, 36. |
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Erigeron rydbergii |
Erigeron divergens |
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Phenology | Flowering Jun–Aug. | Flowering (Feb–)Apr–Oct. |
Habitat | Open subalpine to alpine slopes | 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 | 2000–3200 m (6600–10500 ft) | 60–2000(–2700) m (200–6600(–8900) ft) |
Distribution |
ID; MT; WY
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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 | 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.) |
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Source | FNA vol. 20, p. 293. | FNA vol. 20, p. 339. |
Parent taxa | Asteraceae > tribe Astereae > Erigeron | Asteraceae > tribe Astereae > Erigeron |
Sibling taxa | ||
Synonyms | E. divaricatus, E. accedens, E. incomptus, E. solisaltator | |
Name authority | Cronquist: Brittonia 6: 191. (1947) | Torrey & A. Gray: Fl. N. Amer. 2: 175. (1841) |
Web links |