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big-head aster, large-flower aster

aster du lac Ontario, bottomland aster, Ontario American-aster, Ontario aster

Habit Perennials, 50–100 cm, colonial; woody rhizomatous. Perennials, 20–120 cm, colonial; long-rhizomatous.
Stems

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

1–(2–3), ascending to erect (straight), proximally glabrate, distally uniformly villous or hirsute, or glabrous (var. glabratum).

Leaves

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.

thin, margins scabrous, apices mucronate, abaxial faces usually sparsely to densely strigose or strigillose, sometimes glabrous (var. glabrum), adaxial usually strigose or scabrous, sometimes glabrate or glabrous (var. glabrum);

basal withering by flowering, petiolate to subpetiolate (petioles narrowly winged, ciliate, bases sheathing), blades spatulate to oblanceolate-obovate, 10–40 × 5–10 mm, bases attenuate, margins crenate-serrate, apices acute to rounded;

proximalmost cauline usually withering by flowering, petiolate or sessile (petioles narrowly winged, ± clasping), blades ovate or lance-ovate to elliptic-lanceolate or oblanceolate, 20–80(–12) × 5–35 mm, progressively reduced distally, bases attenuate to cuneate, margins serrate (sometimes coarsely) to crenate-serrate, apices acute to acuminate or short-caudate;

distal sessile, blades elliptic-lanceolate to oblanceolate or lanceolate, (6–)10–80+ × 2–25 mm, progressively reduced distally, bases cuneate, margins entire to serrulate, apices acute to acuminate.

Peduncles

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

subsessile or 2–10(–20) mm, ± pilose, bracts 1–5, linear-lanceolate, pilose, grading into phyllaries.

Involucres

campanulate, 8.5–12 mm.

campanulate, 3–5.5 mm.

Ray florets

14–35;

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

(10–)15–26;

corollas usually white, rarely pinkish or light purple to blue, laminae 3.5–5.5(–8) × 0.5–1.5 mm.

Disc florets

25–35;

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

12–25;

corollas cream or light yellow turning magenta or purple (ampliate), 2.5–4(–4.5) mm, tubes shorter than funnelform throats, lobes slightly spreading to reflexed, lanceolate, 0.7–1.1 mm.

Phyllaries

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.

in (3–)4–6 series, unequal, appressed or ± spreading, linear-obovate (outer) to oblong-lanceolate to linear (inner), bases indurate 1/3–3/4, margins narrowly scarious to apices, erose, hyaline, ciliate, green zones lanceolate, apices acute to acuminate, mucronulate, faces (outer) sparsely pilose or glabrous (var. glabratum), (inner) glabrous.

Heads

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

in ample, open, paniculiform arrays, branches ± ascending or divaricate to long-arching, ± secund.

Cypselae

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

pappi tan, 5.5–6 mm.

gray or tan, oblong-obovoid, sometimes ± compressed, 1.2–1.8(–2) mm, 3–5-nerved, faces strigillose;

pappi whitish to white, 3–3.5 mm.

2n

= 30, 60.

Symphyotrichum grandiflorum

Symphyotrichum ontarionis

Phenology Flowering (Sep–)Oct(–Nov).
Habitat Sandy soils, sand hills, roadsides, edges of deciduous woods and thickets
Elevation 0–200+ m (0–700+ ft)
Distribution
from FNA
NC; SC; VA
[WildflowerSearch map]
[BONAP county map]
from FNA
AL; IA; IL; IN; KS; KY; LA; MI; MN; MO; MS; NC; NE; NY; OK; PA; SD; TN; TX; VT; WI; ON; QC
[WildflowerSearch map]
[BONAP county map]
Discussion

Varieties 2 (2 in the flora).

Symphyotrichum ontarionis is often confused with S. lateriflorum, from which it can be distinguished by its shorter disc corolla lobes and abaxial leaf faces either moderately to densely hairy or glabrous to glabrate (var. glabratum), and without hairs along midveins (as is typical of S. lateriflorum).

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

Key
1. Abaxial leaf faces moderately to densely hairy
var. ontarionis
1. Abaxial leaf faces glabrous or glabrate
var. glabratum
Source FNA vol. 20, p. 484. FNA vol. 20, p. 518.
Parent taxa Asteraceae > tribe Astereae > Symphyotrichum > subg. Virgulus 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. 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
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. 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
Subordinate taxa
S. ontarionis var. glabratum, S. ontarionis var. ontarionis
Synonyms Aster grandiflorus, Virgulus grandiflorus Aster ontarionis, Aster missouriensis
Name authority (Linnaeus) G. L. Nesom: Phytologia 77: 283. (1995) (Wiegand) G. L. Nesom: Phytologia 77: 287. (1995)
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