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rigid whitetop aster

big-head aster, large-flower aster

Habit Perennials, 40–100 cm, usually colonial, sometimes ± cespitose; short-(seldom long-)rhizomatous. Perennials, 50–100 cm, colonial; woody rhizomatous.
Stems

1–2+, erect (straight to slightly flexuous, sometimes robust), glabrous.

1–5+, erect (stout, brown), proximally ± hispid, distally sparsely strigose, distally stipitate-glandular.

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.

stiff (dark green), greatly reduced distally, margins entire, scabrous;

basal early deciduous, sessile, blades (3-nerved) oblanceolate, 40–80 × 4–12 mm, bases attenuate, apices obtuse to acute, faces sparsely scabrous;

proximal cauline usually withered by flowering, sessile, blades oblanceolate to lanceolate-oblong, 20–60 × 5–20 mm, bases cordate-clasping, apices acute, mucronulate, faces glabrate to sparsely scabrous, stipitate-glandular;

distal sessile, blades lanceolate to oblong, 20–40 × 5–8 mm, bases cuneate, apices acute, mucronulate to white-spinulose, faces glabrous or scabrous, sparsely stipitate-glandular.

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.

3–5 cm, short-strigose, stipitate-glandular, bracts spreading to reflexed, lanceolate-oblong, 5–10 mm, little reduced distally, grading into phyllaries.

Involucres

campanulate, (6–)7–10 mm.

campanulate, 8.5–12 mm.

Ray florets

13–30;

corollas blue to purple, laminae (10–)15–17 × 1.6–3 mm.

14–35;

corollas light to reddish purple, laminae 11–15(–20) × 1.5–2.5 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.

25–35;

corollas yellow becoming reddish purple, 5.5–8 mm, lobes narrowly triangular, 0.7–1 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).

in 3–4 series, spatulate-oblanceolate, unequal, bases ± indurate, margins scarious, green zones covering distal portion, apices spreading to strongly reflexed, faces sparsely scabrous, moderately stipitate-glandular.

Heads

in broad (appearing ± corymbiform) or narrow, paniculiform to ± racemiform arrays, branches usually long (to 10 cm), ascending to divaricate.

in racemiform to paniculiform arrays, branches patent or ascending with 1–5+ heads.

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.

light brown, cylindric to narrowly obovoid, ± compressed, 3–4.5 mm, 7–10-nerved (brown), faces moderately strigose;

pappi tan, 5.5–6 mm.

2n

= 48.

= 30, 60.

Symphyotrichum retroflexum

Symphyotrichum grandiflorum

Phenology Flowering Aug–Oct. Flowering (Sep–)Oct(–Nov).
Habitat Moist meadows, moist woodlands, dry, open, pine or oak woods, wooded roadsides Sandy soils, sand hills, roadsides, edges of deciduous woods and thickets
Elevation 400–1500 m (1300–4900 ft) 0–200+ m (0–700+ ft)
Distribution
from FNA
AL; GA; NC; SC; TN; VA
[WildflowerSearch map]
[BONAP county map]
from FNA
NC; SC; VA
[WildflowerSearch map]
[BONAP county map]
Discussion

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.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 20, p. 510. FNA vol. 20, p. 484.
Parent taxa Asteraceae > tribe Astereae > Symphyotrichum > subg. Symphyotrichum > sect. Symphyotrichum Asteraceae > tribe Astereae > Symphyotrichum > subg. Virgulus
Sibling taxa
S. adnatum, S. anomalum, S. anticostense, S. ascendens, S. boreale, S. bracteolatum, S. campestre, S. chapmanii, S. chilense, S. ciliatum, S. ciliolatum, S. concolor, S. cordifolium, S. cusickii, S. defoliatum, S. depauperatum, S. drummondii, S. dumosum, S. elliottii, S. ericoides, S. eulae, S. falcatum, S. fendleri, S. firmum, S. foliaceum, S. fontinale, S. frondosum, S. georgianum, S. grandiflorum, S. greatae, S. hallii, S. hendersonii, S. jessicae, S. laeve, S. lanceolatum, S. lateriflorum, S. laurentianum, S. lentum, S. molle, S. nahanniense, S. novae-angliae, S. novi-belgii, S. oblongifolium, S. ontarionis, S. oolentangiense, S. parviceps, S. patens, S. phlogifolium, S. pilosum, S. plumosum, S. porteri, S. potosinum, S. praealtum, S. pratense, S. prenanthoides, S. priceae, S. puniceum, S. pygmaeum, S. racemosum, S. rhiannon, S. robynsianum, S. sericeum, S. shortii, S. simmondsii, S. spathulatum, S. subspicatum, S. subulatum, S. tenuifolium, S. tradescantii, S. turbinellum, S. undulatum, S. urophyllum, S. walteri, S. welshii, S. yukonense, S. ×amethystinum
S. adnatum, S. anomalum, S. anticostense, S. ascendens, S. boreale, S. bracteolatum, S. campestre, S. chapmanii, S. chilense, S. ciliatum, S. ciliolatum, S. concolor, S. cordifolium, S. cusickii, S. defoliatum, S. depauperatum, S. drummondii, S. dumosum, S. elliottii, S. ericoides, S. eulae, S. falcatum, S. fendleri, S. firmum, S. foliaceum, S. fontinale, S. frondosum, S. georgianum, S. greatae, S. hallii, S. hendersonii, S. jessicae, S. laeve, S. lanceolatum, S. lateriflorum, S. laurentianum, S. lentum, S. molle, S. nahanniense, S. novae-angliae, S. novi-belgii, S. oblongifolium, S. ontarionis, S. oolentangiense, S. parviceps, S. patens, S. phlogifolium, S. pilosum, S. plumosum, S. porteri, S. potosinum, S. praealtum, S. pratense, S. prenanthoides, S. priceae, S. puniceum, S. pygmaeum, S. racemosum, S. retroflexum, S. rhiannon, S. robynsianum, S. sericeum, S. shortii, S. simmondsii, S. spathulatum, S. subspicatum, S. subulatum, S. tenuifolium, S. tradescantii, S. turbinellum, S. undulatum, S. urophyllum, S. walteri, S. welshii, S. yukonense, S. ×amethystinum
Synonyms Aster retroflexus, Aster curtisii Aster grandiflorus, Virgulus grandiflorus
Name authority (Lindley ex de Candolle) G. L. Nesom: Phytologia 77: 291. (1995) (Linnaeus) G. L. Nesom: Phytologia 77: 283. (1995)
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