Erigeron subtrinervis |
Erigeron tracyi |
|
---|---|---|
three-vein fleabane, threenerve fleabane |
running fleabane |
|
Habit | Perennials, 15–90 cm; rhizomatous to subrhizomatous, fibrous-rooted, caudices usually branched, woody, thick. | Annuals, biennials, or short-lived perennials, 2.5–8(–12, 18) cm; usually taprooted, sometimes fibrous-rooted, caudices simple or branched. |
Stems | erect, moderately to densely hirsute (hairs 0.5–0.8 mm), eglandular. |
first erect (greenish proximally), then producing herbaceous, leafy, prostrate runners (stoloniform branches, sometimes with rooting plantlets at tips), densely hirsutulous (hairs spreading-deflexed, of relatively even lengths and orientations), sparsely minutely glandular. |
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). |
mostly basal (persistent in early season); blades oblanceolate to spatulate (obovate-elliptic laminae), 10–30(–60) × 3–6(–12) mm, cauline abruptly reduced distally, margins entire, dentate, or lobed, faces densely hirsute, eglandular. |
Involucres | 6–9 × 13–20 mm. |
3.5–4.5(–6) × 6–9(–12) mm. |
Ray florets | 100–150; corollas blue to lavender, 7–18 mm (ca. 1 mm wide), laminae coiling at tips. |
60–130; corollas white, often purplish abaxially, sometimes with an abaxial midstripe, 5–9 mm, laminae not coiling or reflexing. |
Disc corollas | 4–5 mm. |
2–3 mm (throats indurate and slightly inflated). |
Phyllaries | in 2–3(–4) series, moderately to densely hirsute, minutely glandular. |
in 3–4 series, sparsely to moderately hirsute, minutely glandular. |
Heads | 1–6(–21) in corymbiform arrays. |
1(–3 rarely, from midstem or proximal branches). |
Cypselae | 1.6–2 mm, 2(–4)-nerved, faces sparsely strigose; pappi: outer of setae, inner of 20–30 bristles. |
0.7–1.3 mm, 2-nerved, faces sparsely strigose; pappi: outer of setae, inner of 12–16 bristles. |
2n | = 27. |
|
Erigeron subtrinervis |
Erigeron tracyi |
|
Phenology | Flowering (Jun–)Jul–Sep. | Flowering Mar–Oct. |
Habitat | Opening and margins, roadsides, often shaded, ponderosa pine, pine-fir, mixed conifer, aspen | Desert scrub, grassy slopes, oak chaparral, pinyon-juniper woodlands, Douglas fir-ponderosa pine |
Elevation | 1800–3000(–3500) m (5900–9800(–11500) ft) | 700–2300(–2400) m (2300–7500(–7900) ft) |
Distribution |
CO; ID; MT; ND; NE; NM; SD; UT; WY
|
AZ; CO; KS; NM; NV; OK; TX; UT; Mexico (Baja California, Chihuahua, Coahuila, Durango, Sonora, Zacatecas)
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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.) |
In March through June, plants of Erigeron tracyi produce leaves in a basal rosette usually with a single, erect, monocephalous, stem. Stoloniform branches are soon formed (often recognized on pressed specimens by the leaves mostly on one side of the branches), and by the end of the season (August through October), prostrate runners are usually evident, sometimes forming terminal, rooting plantlets. Erigeron tracyi is similar in habit to E. flagellaris, particularly in the herbaceous stolons or stoloniform branches; the stem pubescence of E. tracyi is different, the stolons much less commonly produce rooting plantlets at the tips, and the plants tend to be perennial with woody or lignescent caudices, although they are variable both in habit and duration. Apparent hybrids with E. modestus and E. flagellaris are occasionally encountered, and the most common form of E. tracyi is perhaps (speculative) a stabilized, apomictic hybrid between the latter and E. divergens. All chromosome counts thus far have shown E. tracyi to be triploid and asynaptic. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 20, p. 330. | FNA vol. 20, p. 340. |
Parent taxa | Asteraceae > tribe Astereae > Erigeron | Asteraceae > tribe Astereae > Erigeron |
Sibling taxa | ||
Synonyms | E. glabellus var. mollis, E. speciosus var. mollis | E. cinereus, E. colomexicanus, E. commixtus, E. divergens var. cinereus |
Name authority | Rydberg ex Porter & Britton: Mem. Torrey Bot. Club 5: 328. (1894) | Greene: Pittonia 5: 59. (1902) |
Web links |