Symphyotrichum ×amethystinum |
Symphyotrichum frondosum |
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amethyst aster, aster, hybrid aster |
alkali aster, leafy annual American-aster, short-ray alkali aster, short-ray aster |
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Habit | Perennials, cespitose, 30–120 cm; with thick, woody, short-branched caudices at ends of fleshy rhizomes. | Annuals or sometimes perennials, 5–140 cm. |
Stems | 1–5+, erect (light brown to grayish brown), densely hispidulo-hirsute. |
1–6+, decumbent to erect (straight), glabrous. |
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 (basal sometimes serrulate), sometimes ciliate or remotely scabrous, acute to ± obtuse, faces glabrous; basal withering by flowering, petiolate, blades oblanceolate to spatulate, 20–115 × 2–15 mm [cult.], bases attenuate; proximal cauline withering by flowering; cauline subpetiolate or sessile (distal), blades oblanceolate to linear, 10–80 × 1.5–10 mm, reduced distally, bases cuneate. |
Peduncles | hispid, bracts 1–3+, oblong-lanceolate, 3–5 mm, not grading into phyllaries. |
glabrous, bracts linear. |
Involucres | campanulate to hemispheric, 4–6 mm. |
narrowly campanulate, 5–9 mm. |
Ray florets | 20–35; corollas azure blue to violet or lavender, laminae 5–10 × 0.6–1.2 mm. |
90–110 in 4–5+ series; corollas pink to pinkish white, laminae 1.5–2 × 0.1–0.2 mm (surpassing style branches, barely surpassing disc corollas; tubes ± 3 mm). |
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. |
± 37; corollas yellow, 4.4–5.2 mm, barely ampliate, tubes much longer than cylindric limbs, lobes lanceolate, ± 0.3 mm. |
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 3–4 series, ± spreading, oblong-oblanceolate or -lanceolate to obovate, subequal to ± unequal, linear-lanceolate or linear (innermost), bases scarious, margins narrowly scarious, hyaline, erose, ciliolate, green zones (outer) foliaceous, (inner) lanceolate, apices obtuse to rounded, inner acute, mucronulate, faces glabrous. |
Heads | in ample, leafy, paniculiform arrays, branches ascending, sometimes secund (heads often crowded). |
(radiate) in narrow, paniculiform to spiciform arrays, branches often in axils of nearly every leaf, ascending. |
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. |
tan, obovoid, ± compressed, 2 mm, 2–3-nerved, faces strigillose; pappi white to yellowish, 6.3–7.5 mm. |
2n | = 10. |
= 14. |
Symphyotrichum ×amethystinum |
Symphyotrichum frondosum |
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Phenology | Flowering Aug–Oct. | Flowering Aug–Oct. |
Habitat | Fields, prairies, disturbed grounds | Moist, usually saline soils, summer-receding shores of lakes or ponds, vernally moist, alkaline bottoms, marshes, often in steppes |
Elevation | 200–400 m (700–1300 ft) | 10–2200 m (0–7200 ft) |
Distribution |
CO; CT; IA; IL; IN; KY; MA; MD; MN; MO; ND; NE; NJ; NY; PA; RI; VT; WA; WI; ON |
AZ; CA; CO; ID; NM; NV; OR; UT; WA; WY; BC; Mexico (Baja California)
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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.) |
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Source | FNA vol. 20, p. 497. | FNA vol. 20, p. 499. |
Parent taxa | ||
Sibling taxa | ||
Synonyms | Aster amethystinus, Virgulus ×amethystinus | Tripolium frondosum, Aster frondosus, Brachyactis frondosa |
Name authority | (Nuttall) G. L. Nesom: Phytologia 77: 294. (1995) | (Nuttall) G. L. Nesom: Phytologia 77: 282. (1995) |
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