Symphyotrichum spathulatum |
Symphyotrichum retroflexum |
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western aster, western mountain aster |
rigid whitetop aster |
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Habit | Perennials, 20–80 cm, colonial; long-rhizomatous. | Perennials, 40–100 cm, usually colonial, sometimes ± cespitose; short-(seldom long-)rhizomatous. | ||||||||
Stems | 1–5+, ascending to erect, glabrous or sparsely puberulent. |
1–2+, erect (straight to slightly flexuous, sometimes robust), glabrous. |
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Leaves | thin, margins entire, apices acute, faces glabrous or sparsely puberulent; basal persistent, petiolate, blades narrowly elliptic to obovate, 50–150 × 3–15 mm, attenuate, margins entire; proximal cauline sessile or subpetiolate, blades linear to narrowly elliptic, 50–150 × 2–15 mm, bases attenuate or cuneate; distal sessile, blades 30–60 × 2–10 mm, reduced distally, bases cuneate to rounded. |
thin to firm, margins slightly recurved, scabrous, faces glabrous; basal mostly withering by flowering, petiolate (petioles narrowly winged, sheathing), blades lanceolate-ovate to ovate or spatulate, 25–110 × 10–40 mm, bases usually rounded to attenuate, seldom ± cordate, margins serrulate to shallowly serrate, apices obtuse to acute; proximal cauline often withering by flowering, petiolate (petioles ± widely winged, ± clasping), blades lance-ovate or narrowly ovate, 50–95 × 19–31 mm, bases usually rounded to attenuate, sometimes cuneate, rarely subcordate, margins serrate to serrulate; distal winged-petiolate or subpetiolate or sessile, blades lance-ovate or narrowly ovate to lanceolate or sometimes linear (in arrays), 7–1.5 × 3–31 mm, gradually and strongly reduced distally, bases cuneate, scarcely or not clasping, to slightly rounded and ± clasping, margins serrulate or entire, apices acute to acuminate. |
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Peduncles | sparsely hairy, bracts 0–3+. |
(when present) 0.2–1.5 cm, densely pilose or pilosulous, bracts 1–6+, lanceolate to oblong-lanceolate, foliaceous to distally grading into phyllaries. |
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Involucres | campanulate, 5–10 mm. |
campanulate, (6–)7–10 mm. |
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Ray florets | 15–40; corollas violet, laminae 9–15 × 1–2 mm. |
13–30; corollas blue to purple, laminae (10–)15–17 × 1.6–3 mm. |
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Disc florets | 30-80(–100); corollas yellow, sometimes becoming reddish, 4.5–6 mm, lobes triangular, 0.5–1 mm. |
35–50+; corollas cream to pale yellow becoming pinkish, 5.8–6.8 mm, tubes shorter than funnelform throats, lobes lanceolate, 0.9–1.2 mm, glabrous. |
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Phyllaries | in 3–5 series, narrowly oblong or linear (outer) to linear (inner), unequal, bases indurate, margins entire, green zones elliptic to lanceolate, apices usually acute, sometimes obtuse, faces glabrous or ± puberulent. |
in 3–4(–5) series, broadly lanceolate constricted to narrow oblong bases (outer) to oblong-lanceolate or linear-lanceolate (inner), ± unequal, bases indurate 1/10–1/5 (outer) to 4/5+ (inner), margins hyaline, narrowly scarious, erose (indurate portion), sparsely ciliolate (foliaceous portion), green zones foliaceous (outer) to distal 1/5–1/4 foliaceous (inner), basally truncate to lanceolate, apices spreading to squarrose, acute to acuminate, mucronulate, abaxial faces glabrous or glabrate, adaxial strigillose (foliaceous portion). |
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Heads | in corymbiform to paniculiform arrays, branches usually few. |
in broad (appearing ± corymbiform) or narrow, paniculiform to ± racemiform arrays, branches usually long (to 10 cm), ascending to divaricate. |
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Cypselae | brown, cylindric to obovoid, not compressed, 2.5–3.5 mm, ± 4-nerved, faces hairy; pappi whitish, 5–7 mm. |
tan, obovoid to oblanceoloid, compressed, 3–3.9 mm, 4–6-nerved, faces glabrous or sparsely strigillose; pappi whitish to reddish, 5.3–6 mm. |
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2n | = 48. |
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Symphyotrichum spathulatum |
Symphyotrichum retroflexum |
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Phenology | Flowering Aug–Oct. | |||||||||
Habitat | Moist meadows, moist woodlands, dry, open, pine or oak woods, wooded roadsides | |||||||||
Elevation | 400–1500 m (1300–4900 ft) | |||||||||
Distribution |
CA; CO; ID; MT; NM; NV; OR; UT; WA; WY; AB; BC; NT; nw Mexico
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AL; GA; NC; SC; TN; VA
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Discussion | Varieties 3 (3 in the flora). Symphyotrichum spathulatum is a variable species, widespread in montane regions of western North America. It hybridizes with S. bracteolatum, S. foliaceum, and S. hendersonii. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Symphyotrichum retroflexum is known only from the Appalachian Blue Ridges. It is possible that the species is an allopolyploid derived from members of subsections Cordifolii and Symphyotrichum. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 20, p. 534. | FNA vol. 20, p. 510. | ||||||||
Parent taxa | Asteraceae > tribe Astereae > Symphyotrichum > subg. Symphyotrichum > sect. Occidentales | Asteraceae > tribe Astereae > Symphyotrichum > subg. Symphyotrichum > sect. Symphyotrichum | ||||||||
Sibling taxa | ||||||||||
Subordinate taxa | ||||||||||
Synonyms | Aster spathulatus | Aster retroflexus, Aster curtisii | ||||||||
Name authority | (Lindley) G. L. Nesom: Phytologia 77: 291. (1995) | (Lindley ex de Candolle) G. L. Nesom: Phytologia 77: 291. (1995) | ||||||||
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