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

Nahanni aster

Habit Perennials, 20–120 cm, colonial; long-rhizomatous. Perennials, 7–39 cm, cespitose; slender, woody, short-rhizomatous (rhizomes of season shallow- or deep-seated, not producing rosettes near parent stems).
Stems

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

1, ascending to decumbent (slender, green to reddish brown), glabrate or sparsely short woolly-pilose in lines or zones, more densely so distally.

Leaves

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.

(light green, abaxial sometimes becoming much darker) thin to firm, margins entire, scabrous, apices mucronulate, faces glabrous;

basal persistent or withering by flowering, petiolate, blades oblanceolate to short-spatulate, 10–130 × 2–8 mm, bases cuneate to attenuate, margins rarely sparsely serrulate, apices obtuse, faces glabrous;

proximal cauline persistent or withering by flowering, sessile, blades oblanceolate to linear lanceolate, 13–60 × 2–6 mm, bases ± clasping, apices acute;

distal sessile, blades linear to linear-lanceolate, 10–36 × 1–4 mm, reduced distally, bases subauriculate, subclasping to ± clasping.

Peduncles

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

10–70 mm, sparsely to moderately short-strigose, bracts 0–10, lanceolate, often foliaceous, reduced distally.

Involucres

campanulate, 3–5.5 mm.

cylindro-campanulate, 4.7–7.4 mm.

Ray florets

(10–)15–26;

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

15–41;

corollas white to pale rose, often becoming rose-violet, laminae 5–13 × 0.7–1.8 mm.

Disc florets

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.

20–60;

corollas yellow turning reddish with age, 3.7–6.6 mm, tubes shorter than funnelform throats, lobes erect to spreading, lanceolate, 0.4–0.8 mm.

Phyllaries

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.

in 3–4 series, outer spatulate, inner lanceolate, ± unequal to subequal, bases indurate, margins reddish, papery, erose-ciliate, green zones lanceolate, apices acute, faces glabrous.

Heads

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

usually borne singly or in open, paniculiform arrays (sometimes terminating lateral branches arising from decumbent stems or from proximal stem branches), branches few.

Cypselae

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.

tan (nerves stramineous), obovoid, compressed, 2–3 mm, 3–5-nerved, faces strigillose;

pappi white, 4–6.5 mm.

2n

= 16.

Symphyotrichum ontarionis

Symphyotrichum nahanniense

Phenology Flowering Aug–Sep.
Habitat Stream banks near hot mineral springs
Elevation ± 1000 m (± 3300 ft)
Distribution
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]
from FNA
NT
[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.)

Of conservation concern.

Symphyotrichum nahanniense is known only from the South Nahanni River (Mackenzie Mountains), Nahanni National Park.

(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. 518. FNA vol. 20, p. 523.
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. 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. 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
Subordinate taxa
S. ontarionis var. glabratum, S. ontarionis var. ontarionis
Synonyms Aster ontarionis, Aster missouriensis Aster nahanniensis
Name authority (Wiegand) G. L. Nesom: Phytologia 77: 287. (1995) (Cody) Semple: in J. C. Semple et al., Cult. Native Asters Ontario, 134. (2002)
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