Symphyotrichum boreale |
Symphyotrichum frondosum |
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aster boréal, northern bog aster, rush American-aster, rush aster, rush or slender white or northern bog aster, slender white aster |
alkali aster, leafy annual American-aster, short-ray alkali aster, short-ray aster |
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Habit | Perennials (5.5–)13–85 cm, colonial; slender (0.6–2.8 mm diam.), long-rhizomatous (rhizomes of season shallow- or deep-seated, not producing rosettes near parent stems). | Annuals or sometimes perennials, 5–140 cm. |
Stems | 1–3+, erect (straight, slender, often reddish to slightly glaucous proximally), glabrous. |
1–6+, decumbent to erect (straight), glabrous. |
Leaves | stiff, margins entire to sparsely subserrulate, revolute, scabrellous, apices mucronulate, sometimes with callous point, faces glabrous, abaxial midveins sometimes sparsely strigillose; basal withering by flowering, subpetiolate to petiolate, petioles winged, base dilated, sheathing, eciliate, blades linear-oblanceolate to ovate or suborbiculate, 20–150 × 5–60 mm, bases attenuate, margins shallowly serrate or entire, apices obtuse to rounded; proximal cauline withering by flowering, sessile or subpetiolate, petioles widely winged, bases strongly clasping, blades linear-lanceolate to linear, 15–90 × 2–12 mm, bases attenuate to cuneate or subauriculate, ± clasping, apices obtuse to acute; distal sessile, blades linear-lanceolate (sometimes lanceolate) to linear, (40–)60–150 × 2–6(–8) mm, ± reduced distally, bases subauriculate, subclasping, margins entire or sometimes remotely serrulate, apices acute. |
thin, margins entire (basal sometimes serrulate), sometimes ciliate or remotely scabrous, acute to ± obtuse, faces glabrous; basal withering by flowering, petiolate, blades oblanceolate to spatulate, 20–115 × 2–15 mm [cult.], bases attenuate; proximal cauline withering by flowering; cauline subpetiolate or sessile (distal), blades oblanceolate to linear, 10–80 × 1.5–10 mm, reduced distally, bases cuneate. |
Peduncles | 0.5–5 cm, glabrous, bracts 1–3, remote, linear-lanceolate to linear, reduced distally, not grading into phyllaries (sometimes subtending heads). |
glabrous, bracts linear. |
Involucres | cylindro-campanulate, (4–)5–8 mm. |
narrowly campanulate, 5–9 mm. |
Ray florets | (15–)25–35(–41); corollas white to often pale rose, pale purple or lavender, laminae (7–)10–15(–20) × 1.1–1.5 mm. |
90–110 in 4–5+ series; corollas pink to pinkish white, laminae 1.5–2 × 0.1–0.2 mm (surpassing style branches, barely surpassing disc corollas; tubes ± 3 mm). |
Disc florets | (15–)25–30(–40); corollas cream or pale yellow becoming pink or brown purple, 3.7–6.6 mm, tubes shorter than funnelform throats, lobes triangular, 0.5–1 mm. |
± 37; corollas yellow, 4.4–5.2 mm, barely ampliate, tubes much longer than cylindric limbs, lobes lanceolate, ± 0.3 mm. |
Phyllaries | in 4–5 series, usually appressed, rarely outer recurved, lanceolate or oblong-lanceolate (outer) to linear (innermost) ± unequal to sometimes subequal, bases indurate 1/3–1/2 (sometimes not indurate), margins scarious, erose, hyaline or tinged with reddish purple, sparsely ciliolate, green zones lanceolate to linear-lanceolate, apices acute to acuminate, mucronate to apiculate, often purple or reddish purple (particularly inner), faces glabrous. |
in 3–4 series, ± spreading, oblong-oblanceolate or -lanceolate to obovate, subequal to ± unequal, linear-lanceolate or linear (innermost), bases scarious, margins narrowly scarious, hyaline, erose, ciliolate, green zones (outer) foliaceous, (inner) lanceolate, apices obtuse to rounded, inner acute, mucronulate, faces glabrous. |
Heads | borne singly or in open, often lax, racemiform or paniculiform arrays, branches ascending, sparsely leafy. |
(radiate) in narrow, paniculiform to spiciform arrays, branches often in axils of nearly every leaf, ascending. |
Cypselae | yellowish tan or purple to brownish with purple streaks or grayish tan (nerves stramineous), obovoid, ± compressed, 0.6–2 mm, 3–5-nerved, faces sparsely strigillose; pappi white, 2.7–6.4 mm. |
tan, obovoid, ± compressed, 2 mm, 2–3-nerved, faces strigillose; pappi white to yellowish, 6.3–7.5 mm. |
2n | = 16, 32, 48, 64. |
= 14. |
Symphyotrichum boreale |
Symphyotrichum frondosum |
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Phenology | Flowering Aug–Oct. | Flowering Aug–Oct. |
Habitat | Mostly calcareous areas, fens, marshes, bogs, open cedar-tamarack-spruce swamps, stream and pond margins, wet meadows, swales | Moist, usually saline soils, summer-receding shores of lakes or ponds, vernally moist, alkaline bottoms, marshes, often in steppes |
Elevation | 0–1500+ m (0–4900+ ft) | 10–2200 m (0–7200 ft) |
Distribution |
AK; CO; IA; ID; IL; IN; MA; MI; MN; MT; ND; NE; NH; NJ; NY; OH; PA; SD; VT; WA; WI; WV; WY; AB; BC; MB; NB; NF; NS; NT; NU; ON; PE; QC; SK; YT
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AZ; CA; CO; ID; NM; NV; OR; UT; WA; WY; BC; Mexico (Baja California)
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Discussion | Some of the western populations originally determined as Symphyotrichum boreale in western Wyoming and adjacent Montana are referable to S. welshii. Those of eastern Wyoming, Colorado, and the Black Hills are S. boreale. There is a gap between the ranges of the two species in Wyoming where neither occurs. Symphyotrichum ×longulum (E. Sheldon) G. L. Nesom (syn. Aster longulus E. Sheldon), reported from Minnesota, is the hybrid between S. boreale and S. puniceum var. puniceum. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Source | FNA vol. 20, p. 522. | FNA vol. 20, p. 499. |
Parent taxa | Asteraceae > tribe Astereae > Symphyotrichum > subg. Symphyotrichum > sect. Symphyotrichum | Asteraceae > tribe Astereae > Symphyotrichum > subg. Symphyotrichum > sect. Conyzopsis |
Sibling taxa | ||
Synonyms | Aster laxifolius var. borealis, Aster borealis, Aster franklinianus, Aster junciformis | Tripolium frondosum, Aster frondosus, Brachyactis frondosa |
Name authority | (Torrey & A. Gray) Á. Löve & D. Löve: Taxon 31: 358. (1982) | (Nuttall) G. L. Nesom: Phytologia 77: 282. (1995) |
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