Symphyotrichum ×amethystinum |
|
---|---|
amethyst aster, aster, hybrid aster |
|
Habit | Perennials, cespitose, 30–120 cm; with thick, woody, short-branched caudices at ends of fleshy rhizomes. |
Stems | 1–5+, erect (light brown to grayish brown), densely hispidulo-hirsute. |
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. |
Peduncles | hispid, bracts 1–3+, oblong-lanceolate, 3–5 mm, not grading into phyllaries. |
Involucres | campanulate to hemispheric, 4–6 mm. |
Ray florets | 20–35; corollas azure blue to violet or lavender, laminae 5–10 × 0.6–1.2 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. |
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. |
Heads | in ample, leafy, paniculiform arrays, branches ascending, sometimes secund (heads often crowded). |
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. |
2n | = 10. |
Symphyotrichum ×amethystinum |
|
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 |
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.) |
Source | FNA vol. 20, p. 497. |
Parent taxa | |
Sibling taxa | |
Synonyms | Aster amethystinus, Virgulus ×amethystinus |
Name authority | (Nuttall) G. L. Nesom: Phytologia 77: 294. (1995) |
Web links |