New York Aster

Foodplant / parasite
sporangium of Basidiophora entospora parasitises live Aster novi-belgii

In Great Britain and/or Ireland:
Foodplant / parasite
cleistothecium of Golovinomyces cichoracearum parasitises live Aster novi-belgii

Symphyotrichum novibelgii is morphologically variable (J. Labrecque and L. Brouillet 1996) and this variation appears to have both genetic and environmental bases. The name Aster foliaceus has been misapplied to members of this complex in eastern North America; various other names also have been misused at the specific or subspecific levels. These are clarified under the varieties below. Hybrids of S. novibelgii, probably mostly var. novibelgii or var. elodes, have been reported with S. lanceolatum and S. lateriflorum.

Perennials, 17–100(–140) cm, loosely to densely colonial or some­­times cespitose; long-rhi­zomatous. Stems 1–5+, erect (straight, stout to slender, often reddish), glabrous and hairy in lines distally or sometimes wholly strigoso-pilose (var. villicaule). Leaves thick, firm, ± fleshy, margins scabrous, apices mucronate, faces glabrous, abaxial midveins sometimes villosulous (var. villicaule); basal withering by flowering, petiolate (petioles winged, bases sheathing), blades ovate to ovate-lanceolate or lanceolate, 17–60+ × 6–11+ mm, bases attenuate to cuneate, apices obtuse; proximal cauline withering by flowering, sessile or widely winged-petiolate (petioles clasping), blades lance-ovate or -obovate to elliptic to linear-lanceolate, 40–200 × 4–40 mm, bases cuneate or sometimes slightly attenuate, sometimes rounded or slightly auriculate, slightly clasping, apices acute to acuminate; distal sessile, blades lance-ovate to linear-lanceolate, 13–62 × 3–15 mm, progressively reduced distally, bases cuneate or ± rounded, sometimes slightly auriculate, ± clasping, margins sparsely serrulate or entire. Heads in open to dense, paniculiform arrays, branches ± divaricate to ascending, leafy with remote, small, gradually reduced branch leaves. Peduncles 4–41 mm, glabrous or moderately pilose, bracts 1–3, lanceolate or ovate to linear-oblanceolate, subtending ones sometimes exceeding involucres, sometimes grading into phyllaries. Involucres campanulate, 6–9 mm. Phyllaries in 3–4 series, oblong-oblanceolate or -spatulate (outer) or oblong-lanceolate to linear-lanceolate or linear (inner), ± unequal to subequal, bases indurate ¹ / 5 – ¹ / 3 , margins hyaline, scarious, erose and sparsely ciliolate distally, green zones lanceolate, sometimes foliaceous, apices spreading to ± squarrose, usually acute to obtuse or ± long-acuminate, mucronulate, faces glabrous. Ray florets 15–35; corollas usually blue-violet or purple, rarely pink or white, laminae (6–)10–19 × 0.9–2.1 mm. Disc florets 28–68; corollas yellow becoming reddish brown to purple, 4–7.5 mm, tubes shorter than funnelform-campanulate throats, lobes lanceolate, 1–1.5 mm. Cypselae tan to brown, obovoid, compressed, 2–4 mm, 4–6-nerved, faces sparsely strigose to glabrate; pappi sordid to yellowish, 4–6 mm.

Aster novibelgii Linnaeus, Sp. Pl. 2: 877. 1753

Symphyotrichum novi-belgii (formerly Aster novi-belgii), commonly called New York aster, is a species of flowering plant. It is the type species for Symphyotrichum, a genus in the family Asteraceae, whose species were once considered to be part of the genus Aster. Plants in both these genera are popularly known as Michaelmas daisy because they bloom around September 29, St. Michael’s Day.

The Latin specific epithet novi-belgii (literally "New Belgium") refers not to modern Belgium, but the 17th century Dutch colony New Netherland which was established on land currently occupied by New York state (as Belgica Foederata was the Latin term for the United Netherlands at the time).

Symphyotrichum novi-belgii grows in abandoned fields and wet meadows in eastern Canada and the northeastern United States.