Symphyotrichum ×amethystinum |
Symphyotrichum spathulatum |
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amethyst aster, aster, hybrid aster |
western aster, western mountain aster |
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Habit | Perennials, cespitose, 30–120 cm; with thick, woody, short-branched caudices at ends of fleshy rhizomes. | Perennials, 20–80 cm, colonial; long-rhizomatous. | ||||||||
Stems | 1–5+, erect (light brown to grayish brown), densely hispidulo-hirsute. |
1–5+, ascending to erect, glabrous or sparsely puberulent. |
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Leaves | light green, thin to firm; basal withering by flowering, sessile, blades oblanceolate, 10–40 × 3–10 mm, attenuate, margins usually entire, rarely remotely serrate, piloso-ciliate, apices obtuse, rounded to mucronulate, faces sparsely to moderately strigose; proximal cauline sometimes persistent by flowering, sessile, blades linear or oblong to elliptic-oblanceolate, 40–60 × 3–10 mm, bases rounded or slightly clasping, margins entire, scabrous, apices acute to obtuse, faces ± copiously hirsute; distal sessile, blades oblanceolate, 15–45 × 2–3(–4.5) mm, progressively reduced distally, bases cuneate, margins entire, apices acute, white-spine-tipped, faces sparsely strigose. |
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. |
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Peduncles | hispid, bracts 1–3+, oblong-lanceolate, 3–5 mm, not grading into phyllaries. |
sparsely hairy, bracts 0–3+. |
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Involucres | campanulate to hemispheric, 4–6 mm. |
campanulate, 5–10 mm. |
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Ray florets | 20–35; corollas azure blue to violet or lavender, laminae 5–10 × 0.6–1.2 mm. |
15–40; corollas violet, laminae 9–15 × 1–2 mm. |
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Disc florets | 20–30+; corollas light yellow turning pinkish to purple, 3–4 mm, tubes ca. 1/2 narrowly funnelform throats, lobes triangular, 0.5–0.7 mm, glabrous. |
30-80(–100); corollas yellow, sometimes becoming reddish, 4.5–6 mm, lobes triangular, 0.5–1 mm. |
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Phyllaries | in 3–5 series, linear-lanceolate, ± unequal to subequal, bases ± indurate, margins hyaline proximally, outer distally hispido-scabrous, green zones diamond-shaped, restricted to distal 1/2–1/4, apices (outer) spreading to reflexed, acute, subspinulose, (inner) acuminate, purplish, faces (outer) scabroso-puberulent or strigose, eglandular, inner distally stipitate-glandular. |
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. |
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Heads | in ample, leafy, paniculiform arrays, branches ascending, sometimes secund (heads often crowded). |
in corymbiform to paniculiform arrays, branches usually few. |
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Cypselae | dull purple or brown, obovoid, not compressed, 1.5–2 mm, 7–9-nerved, faces densely sericeous; pappi tan to tawny, sometimes rose to violet-tinged, 3.5–5.5 mm. |
brown, cylindric to obovoid, not compressed, 2.5–3.5 mm, ± 4-nerved, faces hairy; pappi whitish, 5–7 mm. |
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2n | = 10. |
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Symphyotrichum ×amethystinum |
Symphyotrichum spathulatum |
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Phenology | Flowering Aug–Oct. | |||||||||
Habitat | Fields, prairies, disturbed grounds | |||||||||
Elevation | 200–400 m (700–1300 ft) | |||||||||
Distribution |
CO; CT; IA; IL; IN; KY; MA; MD; MN; MO; ND; NE; NJ; NY; PA; RI; VT; WA; WI; ON |
CA; CO; ID; MT; NM; NV; OR; UT; WA; WY; AB; BC; NT; nw Mexico
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Discussion | Symphyotrichum ×amethystinum is the F1 hybrid between S. ericoides and S. novae-angliae, encountered sometimes throughout the area where the two parental species co-occur. It is morphologically intermediate; it has non-spiny, sparsely stipitate-glandular phyllaries and rose-violet rays in mid-sized heads. Forma leucerythros Bemis and forma leucos Bemis have been described within this hybrid and may represent recombinants or normal population color variants. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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.) |
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Key |
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Source | FNA vol. 20, p. 497. | FNA vol. 20, p. 534. | ||||||||
Parent taxa | ||||||||||
Sibling taxa | ||||||||||
Subordinate taxa | ||||||||||
Synonyms | Aster amethystinus, Virgulus ×amethystinus | Aster spathulatus | ||||||||
Name authority | (Nuttall) G. L. Nesom: Phytologia 77: 294. (1995) | (Lindley) G. L. Nesom: Phytologia 77: 291. (1995) | ||||||||
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