Erigeron subtrinervis |
Erigeron caespitosus |
|
---|---|---|
three-vein fleabane, threenerve fleabane |
tuft daisy, tuft fleabane |
|
Habit | Perennials, 15–90 cm; rhizomatous to subrhizomatous, fibrous-rooted, caudices usually branched, woody, thick. | Perennials, 5–25(–30) cm; taprooted, caudices relatively thick, usually branched. |
Stems | erect, moderately to densely hirsute (hairs 0.5–0.8 mm), eglandular. |
decumbent-ascending (greenish proximally), usually densely hirsute to hirtellous (hairs spreading to deflexed, gradually attenuate, basal cells erect), sometimes strigose (in Saskatchewan and Yukon), eglandular. |
Leaves | basal (usually withering by flowering) and cauline; basal blades oblanceolate-spatulate, 30–80 × 6–20(–27) mm, margins entire, faces evenly hirsute to strigoso-hirsute, usually eglandular; cauline blades lanceolate to oblong, oblong-ovate, or broadly ovate, nearly even-sized distally or sometimes mid largest (continuing to immediately proximal to heads, bases clasping to subclasping). |
basal (persistent) and cauline; basal blades (1–)3-nerved, narrowly oblanceolate to spatulate, (10–)20–90(–120) × 2–15 mm, margins entire (apices rounded to obtuse), faces densely hirtellous, eglandular; cauline blades oblong-ovate to linear, ± reduced distally. |
Involucres | 6–9 × 13–20 mm. |
4–7 × 9–18 mm. |
Ray florets | 100–150; corollas blue to lavender, 7–18 mm (ca. 1 mm wide), laminae coiling at tips. |
30–100; corollas white to bluish, 5–15 mm, laminae coiling. |
Disc corollas | 4–5 mm. |
3–4.4 mm. |
Phyllaries | in 2–3(–4) series, moderately to densely hirsute, minutely glandular. |
in 3–4 series, densely hirsuto-canescent to hirtellous (hairs spreading), moderately minutely glandular. |
Heads | 1–6(–21) in corymbiform arrays. |
1–4 (branches from distal 1/2 of stem). |
Cypselae | 1.6–2 mm, 2(–4)-nerved, faces sparsely strigose; pappi: outer of setae, inner of 20–30 bristles. |
1.7–2.2 mm, 2-nerved, faces sparsely strigose; pappi: outer of setae or scales, inner of 15–25 bristles. |
2n | = 18, 36. |
|
Erigeron subtrinervis |
Erigeron caespitosus |
|
Phenology | Flowering (Jun–)Jul–Sep. | Flowering Jun–Aug. |
Habitat | Opening and margins, roadsides, often shaded, ponderosa pine, pine-fir, mixed conifer, aspen | Rocky or sandy, grassy hills, sagebrush-aspen, pinyon-juniper, to spruce and tundra northward |
Elevation | 1800–3000(–3500) m (5900–9800(–11500) ft) | 1300–3000(–3600) m (4300–9800(–11800) ft) |
Distribution |
CO; ID; MT; ND; NE; NM; SD; UT; WY
|
AK; AZ; CO; ID; MT; ND; NE; NM; SD; UT; WA; WY; AB; BC; MB; SK; YT
|
Discussion | Erigeron subtrinervis is variable in vestiture, perhaps reflecting gene exchange with E. speciosus. Erigeron speciosus var. mollis (A. Gray) S. L. Welsh may be a recurrent hybrid; it is identified here within E. subtrinervis. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Erigeron caespitosus as recognized here is highly variable and perhaps justifiably could be divided into more than one taxon. Plants at lower elevations tend to produce tall stems branching above the middle and long, white rays. At higher elevations, especially in Idaho, western Montana, Utah, and Wyoming, stems tend to be shorter and simple and the rays commonly are blue to violet. In the Bitterroot Mountains (Ravalli and Deerlodge counties, Montana), short-stemmed, blue-rayed plants also have strigose cauline vestiture (in contrast to typically deflexed-hirtellous stems); these vestiture variants occur in the same area with plants apparently similar in all other features. Strigose populational variants also occur in Saskatchewan and Yukon, and E. abajoensis, largely distinguished by strigose cauline vestiture, might be considered a regional variant of E. caespitosus. In eastern Idaho and southwestern Montana, plants of E. caespitosus are commonly encountered with cauline leaves obovate and distinctly subclasping. Plants with strongly 3-nerved basal leaves occur in Carbon and Gallatin counties, Montana. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 20, p. 330. | FNA vol. 20, p. 283. |
Parent taxa | Asteraceae > tribe Astereae > Erigeron | Asteraceae > tribe Astereae > Erigeron |
Sibling taxa | ||
Synonyms | E. glabellus var. mollis, E. speciosus var. mollis | |
Name authority | Rydberg ex Porter & Britton: Mem. Torrey Bot. Club 5: 328. (1894) | Nuttall: Trans. Amer. Philos. Soc., n. s. 7: 307. (1840) |
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