Symphyotrichum ×amethystinum |
Symphyotrichum novae-angliae |
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amethyst aster, aster, hybrid aster |
aster de nouvelle-angleterre, New England American-aster, New England aster, New England or michaelmas daisy |
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Habit | Perennials, cespitose, 30–120 cm; with thick, woody, short-branched caudices at ends of fleshy rhizomes. | Perennials, 30–120 cm, cespitose; with thick, woody, branched caudices, or short, fleshy rhizomes, sometimes with woody cormoid portions. |
Stems | 1–5+, erect (light brown to grayish brown), densely hispidulo-hirsute. |
1–5+, erect (stout, light to dark brown, sometimes purplish distally), proximally sparsely to moderately hispiduloso-hirsute or pilose, distally moderately to densely so, stipitate-glandular. |
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. |
(light to dark green) thin, often stiff, margins entire or sometimes with shallow teeth, ciliate; basal withered or withering by flowering, sessile, blades (3-nerved) usually spatulate, sometimes oblanceolate, 20–60 × 5–15 mm, bases attenuate, apices acute, faces sparsely hirsute; proximal cauline withering by flowering, sessile, blades oblong or lanceolate, 50–100 × 5–15(–20) mm, bases auriculate-clasping, margins entire, pustulate-scabrous, apices acute, mucronulate, faces stipitate-glandular, abaxial thinly strigose, adaxial hirsute or hispidulous; distal sessile, blades oblanceolate, 30–80 × 6–15 mm, gradually reduced distally, bases auriculate-clasping, apices acute to obtuse, mucronate to minutely white-spinulose, faces moderately to densely short-soft-hairy, sparsely to moderately stipitate-glandular. |
Peduncles | hispid, bracts 1–3+, oblong-lanceolate, 3–5 mm, not grading into phyllaries. |
dilated distally, 0.3–4 cm, densely short-hairy, stipitate-glandular, bracts 1–4, foliaceous, linear to narrowly lanceolate, densely short-hairy, stipitate-glandular, grading into phyllaries. |
Involucres | campanulate to hemispheric, 4–6 mm. |
campanulate to hemispheric, (5–)7–9(–15) mm. |
Ray florets | 20–35; corollas azure blue to violet or lavender, laminae 5–10 × 0.6–1.2 mm. |
(40–)50–75(-100); corollas dark rose to deep purple (pale pink or white), laminae 9–13 × 0.8–1.3 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. |
50–110; corollas light yellow becoming purple, (4–)4.5–5.5(–7) mm, tubes ± 1/2 narrowly funnelform throats (glabrous or thinly puberulent), lobes triangular, 0.4–0.7 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 3–5(–6) series (dark green to purple-tinged), linear-lanceolate, subequal, outer foliaceous, mid and inner scarious in basal 1/3–1/2, margins stipitate-glandular, apices long-acuminate to acuminate, spreading to reflexed or squarrose, faces glabrous, outer densely stipitate-glandular. |
Heads | in ample, leafy, paniculiform arrays, branches ascending, sometimes secund (heads often crowded). |
in leafy, often crowded, paniculo-corymbiform arrays. |
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. |
dull purple or brown, oblong or obconic, not compressed, 1.8–2.5(–3) × 0.6–1 mm, 7–10-nerved, faces densely sericeous, sparsely stipitate-glandular; pappi tawny (barb tips sometimes rose-tinged), 4.5–6 mm. |
2n | = 10. |
= 10. |
Symphyotrichum ×amethystinum |
Symphyotrichum novae-angliae |
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Phenology | Flowering Aug–Oct. | Flowering Aug–Oct(–Nov). |
Habitat | Fields, prairies, disturbed grounds | Open, moist to wet, sandy or loamy, rich soils, fields, prairies, meadows, marshy grounds, shrubby swamps, fens, shores, thickets, moist edges of woods, roadsides, railroad rights-of-way, somewhat weedy |
Elevation | 200–400 m (700–1300 ft) | 0–1600 m (0–5200 ft) |
Distribution |
CO; CT; IA; IL; IN; KY; MA; MD; MN; MO; ND; NE; NJ; NY; PA; RI; VT; WA; WI; ON |
AL; AR; CO; CT; DC; DE; GA; IA; IL; IN; KS; KY; MA; MD; ME; MI; MN; MO; MS; MT; NC; ND; NE; NH; NJ; NM; NY; OH; OK; OR; PA; RI; SC; SD; TN; UT; VA; WA; WI; WV; WY; MB; NB; NS; ON; QC [Introduced in Europe]
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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.) |
Symphyotrichum novae-angliae is escaped from cultivation and introduced in Montana, Oregon, Utah, Washington, and Wyoming, and has been reported as an ephemeral escape in British Columbia. It possibly escaped from cultivation elsewhere. The Michaelmas daisy is widely sold in the horticultural trade, where cultivars have been developed. Forms have been described that correspond to color genetic variants within natural populations {Aster novae-angliae forma roseus (Desfontaines) Britton; A. novae-angliae forma geneseensis House}; they are not recognized here. Symphyotrichum novae-angliae resembles Canadanthus modestus, but the ranges of the two do not overlap, and the latter has sparsely hairy cypselae with dark ribs. Symphyotrichum novae-angliae hybridizes with S. ericoides, forming the F1 intersectional hybrid S. ×amethystinum. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 20, p. 497. | FNA vol. 20, p. 487. |
Parent taxa | ||
Sibling taxa | ||
Synonyms | Aster amethystinus, Virgulus ×amethystinus | Aster novae-angliae, Virgulus novae-angliae |
Name authority | (Nuttall) G. L. Nesom: Phytologia 77: 294. (1995) | (Linnaeus) G. L. Nesom: Phytologia 77: 287. (1995) |
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