Symphyotrichum retroflexum

(Lindley ex de Candolle) G. L. Nesom

Phytologia 77: 291. 1995.

Common names: Rigid whitetop aster
Basionym: Aster retroflexus Lindley ex de Candolle in A. P. de Candolle and A. L. P. P. de Candolle, Prodr. 5: 244. 1836
Synonyms: Aster curtisii Torrey & A. Gray
Treatment appears in FNA Volume 20. Treatment on page 510. Mentioned on page 473, 475, 500.

Perennials, 40–100 cm, usually colonial, sometimes ± cespitose; short-(seldom long-)rhizomatous. Stems 1–2+, erect (straight to slightly flexuous, sometimes robust), glabrous. Leaves thin to firm, margins slightly recurved, scabrous, faces glabrous; basal mostly withering by flowering, petiolate (petioles narrowly winged, sheathing), blades lanceolate-ovate to ovate or spatulate, 25–110 × 10–40 mm, bases usually rounded to attenuate, seldom ± cordate, margins serrulate to shallowly serrate, apices obtuse to acute; proximal cauline often withering by flowering, petiolate (petioles ± widely winged, ± clasping), blades lance-ovate or narrowly ovate, 50–95 × 19–31 mm, bases usually rounded to attenuate, sometimes cuneate, rarely subcordate, margins serrate to serrulate; distal winged-petiolate or subpetiolate or sessile, blades lance-ovate or narrowly ovate to lanceolate or sometimes linear (in arrays), 7–1.5 × 3–31 mm, gradually and strongly reduced distally, bases cuneate, scarcely or not clasping, to slightly rounded and ± clasping, margins serrulate or entire, apices acute to acuminate. Heads in broad (appearing ± corymbiform) or narrow, paniculiform to ± racemiform arrays, branches usually long (to 10 cm), ascending to divaricate. Peduncles (when present) 0.2–1.5 cm, densely pilose or pilosulous, bracts 1–6+, lanceolate to oblong-lanceolate, foliaceous to distally grading into phyllaries. Involucres campanulate, (6–)7–10 mm. Phyllaries in 3–4(–5) series, broadly lanceolate constricted to narrow oblong bases (outer) to oblong-lanceolate or linear-lanceolate (inner), ± unequal, bases indurate 1/10–1/5 (outer) to 4/5+ (inner), margins hyaline, narrowly scarious, erose (indurate portion), sparsely ciliolate (foliaceous portion), green zones foliaceous (outer) to distal 1/5–1/4 foliaceous (inner), basally truncate to lanceolate, apices spreading to squarrose, acute to acuminate, mucronulate, abaxial faces glabrous or glabrate, adaxial strigillose (foliaceous portion). Ray florets 13–30; corollas blue to purple, laminae (10–)15–17 × 1.6–3 mm. Disc florets 35–50+; corollas cream to pale yellow becoming pinkish, 5.8–6.8 mm, tubes shorter than funnelform throats, lobes lanceolate, 0.9–1.2 mm, glabrous. Cypselae tan, obovoid to oblanceoloid, compressed, 3–3.9 mm, 4–6-nerved, faces glabrous or sparsely strigillose; pappi whitish to reddish, 5.3–6 mm. 2n = 48.

Phenology: Flowering Aug–Oct.
Habitat: Moist meadows, moist woodlands, dry, open, pine or oak woods, wooded roadsides
Elevation: 400–1500 m



Ala., Ga., N.C., S.C., Tenn., Va.


Symphyotrichum retroflexum is known only from the Appalachian Blue Ridges. It is possible that the species is an allopolyploid derived from members of subsections Cordifolii and Symphyotrichum.

Selected References


Lower Taxa

Luc Brouillet +, John C. Semple +, Geraldine A. Allen +, Kenton L. Chambers +  and Scott D. Sundberg† +
(Lindley ex de Candolle) G. L. Nesom +
Aster retroflexus +
Rigid whitetop aster +
Ala. +, Ga. +, N.C. +, S.C. +, Tenn. +  and Va. +
400–1500 m +
Moist meadows, moist woodlands, dry, open, pine or oak woods, wooded roadsides +
Flowering Aug–Oct. +
Aster curtisii +
Symphyotrichum retroflexum +
Symphyotrichum sect. Symphyotrichum +
species +