Symphyotrichum yukonense |
Symphyotrichum bracteolatum |
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Yukon aster |
bract aster, Eaton's aster, Oregon aster |
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Habit | Perennials cespitose or colonial, 5–30 cm; with short, erect, woody caudices from long, thin rhizomes. | Perennials 40–100 cm, cespitose; short-rhizomatous. |
Stems | 1–8+, erect (purplish to brown, slender), villous, more densely so distally, distally moderately stipitate-glandular. |
1–10+, ascending to erect, glabrous or sparsely puberulent. |
Leaves | (yellowish to dark green. |
thin, margins entire or sometimes serrate, apices acute; basal withering by flowering, petiolate, blades narrowly lanceolate, 60–200 × 10–20 mm, attenuate or cuneate, margins usually entire, sometimes serrate, apices acute, faces glabrous or sparsely puberulent; proximalmost cauline sometimes withering by flowering, sessile, blades narrowly lanceolate, 50–150 × 8–25 mm, bases cuneate, often auriculate, apices acute; distal sessile, blades linear to narrowly lanceolate, 20–120 × 3–20 mm, bases cuneate, often auriculate, apices acute. |
Peduncles | ± densely short-villous, ± densely stipitate-glandular, bracts 1–3, foliaceous, reduced. |
sparsely hairy, bracts linear to lanceolate. |
Involucres | campanulate, 7–10 mm. |
campanulate, 5–8 mm. |
Ray florets | (8–)15–30; corollas purple to blue, laminae 5–11 × 0.5–2 mm. |
20–40; corollas white to pink, laminae 7–15 × 1–2 mm. |
Disc florets | 16–38; corollas yellow becoming brown, 4–6.5 mm, lobes triangular, 0.4–0.8 mm. |
35–60+; corollas yellow, 4.5–5 mm, lobes triangular, 0.5–0.75 mm. |
Phyllaries | in 3–4(–5) series, linear-lanceolate, subequal, bases scarious, margins hyaline or purplish, scarious, erose, ciliate or short-stipitate-glandular, green zones herbaceous at least distally, often purplish to purple, apices long-acuminate, spreading to reflexed, faces ± densely villous (outer more so), ± densely stipitate-glandular. |
in 3–5 series, often spreading, oblanceolate (outer) to linear (inner), subequal, outer indurate less than 1/2, bases outer variable, inner scarious, margins entire, scabrous to ciliolate, green zones oblanceolate to elliptic, apices acute to obtuse, often spreading, faces glabrous or sparsely puberulent. |
Heads | usually borne singly, sometimes in open, corymbo-paniculiform arrays, branches ascending. |
in racemiform to narrow, paniculiform arrays, branches usually to 10 cm. |
Cypselae | brown (sometimes purplish, nerves stramineous), narrowly obovoid, ± compressed, ca. 3 mm, 7–10-nerved, faces sparsely to moderately sericeo-strigose; pappi sordid (barb tips sometimes purplish-tinged), 3.5–4.8 mm. |
brown, cylindric to obovoid, not compressed, 2.5–3.5 mm, 1–2-nerved, faces hairy; pappi white, 5–6 mm. |
Midrib | purplish, often prominent) thin, reduced distally, margins entire; basal withering by flowering, winged-petiolate to subpetiolate (petioles ± sheathing), blades narrowly oblanceolate, 8–15 × 1–3 mm, bases attenuate, margins scabrous, apices obtuse to acute, faces glabrous or glabrate; proximal cauline often withering by flowering, sessile or subsessile, blades linear-oblanceolate, 20–70 × 1–4 mm, bases ± clasping, margins ciliate, apices acute, abaxial faces glabrous or midnerve ± sparsely villous, adaxial glabrous or sparsely villous, midnerves ± villous; distal sessile, blades linear-lanceolate, 10–30 × 1–2.5 mm, bases ± subclasping, ± rounded to subauriculate, margins sometimes stipitate-glandular, apices acute, mucronate or white-spinulose, faces glabrous or sparsely villous, short-stipitate-glandular. |
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2n | = 10. |
= 16, 32, 48, 64. |
Symphyotrichum yukonense |
Symphyotrichum bracteolatum |
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Phenology | Flowering Jul–Aug. | Flowering Jul–Aug. |
Habitat | Mud flats, gravelly, stony or silty lakeshores, sometimes saline areas | Moist to wet sunny places, wet thickets, along streams and ditches |
Elevation | 300–1500 m (1000–4900 ft) | 500–3100 m (1600–10200 ft) |
Distribution |
AK; NT; YT |
AZ; CA; CO; ID; MT; NM; NV; OR; UT; WA; WY; AB; BC; SK |
Discussion | Of conservation concern. Symphyotrichum yukonense is distributed disjunctly on the John River in the southern Brooks Range (Alaska), Lake Kluane (Yukon), and the Mackenzie Mountains and middle Mackenzie River (Northwest Territories). It appears closely related to S. pygmaeum. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Source | FNA vol. 20, p. 485. | FNA vol. 20, p. 531. |
Parent taxa | ||
Sibling taxa | ||
Synonyms | Aster yukonensis, Virgulus yukonensis | Aster foliaceus var. eatonii, Aster bracteolatus, Aster eatonii |
Name authority | (Cronquist) G. L. Nesom: Phytologia 77: 294. (1995) | (Nuttall) G. L. Nesom: Phytologia 77: 276. (1994) |
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