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rigid whitetop aster

willow aster, willow-leaf American-aster, willowleaf aster

Habit Perennials, 40–100 cm, usually colonial, sometimes ± cespitose; short-(seldom long-)rhizomatous. Perennials (10–)50–150(–200) cm, colonial; fleshy long-rhizomatous.
Stems

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

1, erect to ascending (stout, ± glaucous or reddish), glabrate to moderately hispidulous-hirsute (mostly in lines) distally.

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.

thick, firm, margins often revolute, scabrous, apices mucronate, abaxial faces glabrous, vein areoles conspicuous, ± isodiametric, adaxial waxy, glabrate to strigose, ± scabrous (distal cauline with axillary leaf clusters, sometimes becoming branches);

basal withering by flowering, petiolate to subpetiolate (petioles winged, bases sheathing, ciliate), blades spatulate, 40–70 × 10–25 mm, bases attenuate, margins entire to shallowly serrate, apices rounded to obtuse;

proximal cauline withering by flowering, sessile (subpetiolate), blades elliptic or lanceolate to oblanceolate or linear-lanceolate, 40–100(–150) × 3–18 mm, progressively reduced distally, bases cuneate, often slightly rounded, apices acute to attenuate, callus-pointed, abaxial faces scabrellous, adaxial glabrous or ± puberulent;

distal sessile, blades ovate or elliptic-lanceolate to lanceolate or linear, 10–85 × 2–17 mm, progressively reduced distally, bases cuneate, margins entire, apices acute or obtuse, callus-pointed.

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.

0.3–2 cm, ± pilose, bracts 5–12+, ascending or recurved-spreading, lance-elliptic to lanceolate or linear-lanceolate, foliaceous, distal closely subtending heads, not grading into phyllaries.

Involucres

campanulate, (6–)7–10 mm.

campanulate, (4–)5–7(–8) mm.

Ray florets

13–30;

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

(6–)20–35;

corollas pale blue-violet to lavender or rose-purple, rarely white, laminae 5–10(–12) × 1–1.7 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.

20–30(–35+);

corollas cream or light yellow turning pinkish purple, 4–6.5 mm, tubes shorter than narrowly funnelform throats, lobes lanceolate, 0.5–1.3 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 4–6 series, appressed, oblong-lanceolate to linear (innermost) (outer sometimes ± foliaceous), unequal, bases indurate 1/2–3/4, margins scarious, erose, hyaline, sparsely ciliolate (often ciliate basally), green zones lanceolate to lance-rhombic, apices sometimes spreading, acute to acuminate, mucronate, often reddish purple apically, faces glabrous.

Heads

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

in ample, foliaceous, usually dense, paniculiform arrays, branches ascending to spreading, ± racemiform.

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.

purple or stramineous with purple, obovoid, sometimes ± compressed, 1.5–2 mm, 4–5-nerved, faces thinly strigillose;

pappi white, 4–6.5 mm.

2n

= 48.

= 32, 48, 64.

Symphyotrichum retroflexum

Symphyotrichum praealtum

Phenology Flowering Aug–Oct. Flowering Aug–Oct.
Habitat Moist meadows, moist woodlands, dry, open, pine or oak woods, wooded roadsides Wet, loamy soils, wet prairies or meadows, lake and stream shores, oak savannas, open woods or thickets, fields, moist banks, ditches, roadsides, recent clearings
Elevation 400–1500 m (1300–4900 ft) 0–400+ m (0–1300+ ft)
Distribution
from FNA
AL; GA; NC; SC; TN; VA
[WildflowerSearch map]
[BONAP county map]
from FNA
AL; AR; CT; DC; DE; FL; IA; IL; IN; KS; KY; LA; MA; MD; ME; MI; MO; MS; NE; NH; NJ; NY; OH; OK; PA; RI; SD; TN; TX; VA; WI; WV; ON; Mexico (Chihuahua, Coahuila, Nuevo Léon) [Introduced in Europe]
[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.)

Symphyotrichum praealtum was reported by H. R. Hinds (2000) as a possible introduced, non-persisting ephemeral in New Brunswick. The species is introduced in central Europe, where it has been confused with S. lanceolatum (J. C. Semple et al. 2002). A. G. Jones (1989) reported hybridization with S. lanceolatum and S. firmum.

G. L. Nesom (1994b, 1997) and J. C. Semple et al. (2002) recognize several varieties within the species: var. praealtum [syn. Aster coerulescens de Candolle, A. praealtus var. coerulescens (de Candolle) A. G. Jones, A. praealtus var. imbricatior Wiegand] (2n = 32); var. angustior (Wiegand) G. L. Nesom (syn. A. praealtus var. angustior Wiegand) (2n = 64); var. nebraskense (Britton) G. L. Nesom (syn. A. praealtus var. nebraskensis Britton); var. subasperum (Lindley) G. L. Nesom [syn. A. praealtus var. subasper (Lindley) Wiegand, A. subasper Lindley]; and var. texicola (Wiegand) G. L. Nesom (syn. A. praealtus var. texicola Wiegand). Some of these varieties deserve recognition, but the validity of others needs confirmation.

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

Source FNA vol. 20, p. 510. FNA vol. 20, p. 521.
Parent taxa Asteraceae > tribe Astereae > Symphyotrichum > subg. Symphyotrichum > sect. Symphyotrichum Asteraceae > tribe Astereae > Symphyotrichum > subg. Symphyotrichum > sect. Symphyotrichum
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. 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. 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 praealtus, Aster salicifolius
Name authority (Lindley ex de Candolle) G. L. Nesom: Phytologia 77: 291. (1995) (Poiret) G. L. Nesom: Phytologia 77: 289. (1995)
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