Symphyotrichum robynsianum |
Symphyotrichum porteri |
|
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aster à longues feuilles, longleaf aster, Robyns' aster |
Porter's or smooth white aster, smooth white aster |
|
Habit | Perennials, 10–80 cm, colonial; long-rhizomatous. | Perennials, 10–50 cm, cespitose; usually with branched caudices, sometimes long-rhizomatous. |
Stems | 1, erect (± flexuous, often reddish), glabrous, hairy in lines distally. |
1–4+, ascending to erect (straight), glabrous. |
Leaves | stiff, margins sparsely serrulate or entire, ± revolute, scabrous, apices acute to acuminate, mucronulate, faces glabrous, sometimes midveins hairy; basal withering by flowering, long-petiolate, petioles narrowly winged, bases sheathing, blades lanceolate, ca. 20 × 3–5 mm, slightly attenuate to narrowly cuneate; proximal cauline withering by flowering, sessile or subpetiolate, blades linear-lanceolate to -oblanceolate, 100–200 × 4–8 mm, bases cuneate to attenuate, clasping; distal sessile, blades linear-lanceolate to linear, 10–110 × 1–7 mm, progressively reduced distally, bases cuneate to rounded, slightly clasping or not, margins entire. |
thin, margins usually entire, sometimes very sparsely serrulate distally, scabrous, apices acute, mucronulate, faces glabrous; basal usually deciduous at flowering (new winter rosettes developed by flowering), petiolate (petioles narrow or ± winged, then appearing sessile, slightly sheathing, ciliate), blades oblanceolate to obovate or spatulate, 5–45+ × 2–6 mm, cuneate, apices obtuse; proximal cauline usually withering by flowering, petiolate or sessile (petioles winged, slightly clasping, ciliate), blades oblanceolate or lanceolate to linear-oblanceolate or -lanceolate, 40–80(–90) × 2–5(–6) mm, bases cuneate; distal sessile, blades linear-lanceolate to linear, ± falcate, 8–60 × 0.5–3 mm, reduced distally, bases cuneate to rounded-cuneate. |
Peduncles | glabrous or ± densely pilose in lines, bracts 1–4, linear, sometimes inrolled distally, clasping, ciliate, distal 1–2 often subtending and surpassing involucres. |
0.2–2.8 cm, bracteate, glabrous, bracts 1–3, linear to linear-lanceolate. |
Involucres | campanulate, 5–8.5 mm. |
campanulate to cylindro-campanulate, 3.6–5(–6) mm. |
Ray florets | 20–35; corollas dark blue-violet, seldom white, laminae 8–13 × 1–1.5 mm. |
(12–)20–34(–42); corollas usually white, seldom pinkish, laminae 6.8–12 × 0.7–1.8 mm. |
Disc florets | (18–)23–40; corollas yellow, 4–6.5 mm, tubes shorter than funnelform throats, lobes lanceolate, 0.8–1 mm. |
(30–)40–75(–103); corollas pale yellow becoming pink and later brown, (2.8–)3.1–3.9(–4.9) mm, tubes much shorter than narrowly funnelform throats, lobes triangular, (0.3–)0.5–0.7(–0.8) mm. |
Phyllaries | in 3–4 series, oblong-lanceolate, subequal, bases indurate 1/3–3/4, margins scarious, erose, hyaline, ciliate proximally, sparsely ciliolate distally, green zones lanceolate to linear, sometimes outer ± foliaceous, apices acuminate to long-acuminate, often foliaceous, mucronate to apiculate, faces glabrous, eglandular. |
in 4–6 series, linear-lanceolate to -oblanceolate (outer) or oblong-lanceolate (inner), unequal, bases indurate 1/4–3/4 (sometimes outermost foliaceous), margins proximally narrowly scarious, erose, hyaline, distally ciliolate, green zones lanceolate, apices acute, ± spreading, involute, mucronulate, faces glabrous. |
Heads | in elongate, open, narrow, paniculiform or racemiform arrays, branches ascending, short, leafy, branch leaves smaller and reduced distally (heads 1–3 per branch). |
in paniculiform arrays, branches ascending, ± densely leafy with narrow branch leaves. |
Cypselae | tan, obovoid, compressed, ca. 2.2–2.4 mm, 5–6-nerved, faces sparsely strigillose; pappi pinkish, 7–8 mm. |
purple to stramineous, obovoid to oblanceoloid, compressed, 1–2 mm, 4–5-nerved, faces sparsely, finely strigillose; pappi white, 1.2–3.5 mm. |
2n | = 64, 80. |
= 16. |
Symphyotrichum robynsianum |
Symphyotrichum porteri |
|
Phenology | Flowering Aug–Sep. | Flowering late Jul–Sep. |
Habitat | Wet or damp, open, sandy, gravelly, or rocky grounds, often calcareous, cracks in rocky stream or lake shores, limestone alvars, seasonally wet glades and swales, jackpine outwash plains | Lower montane |
Elevation | 10–400 m (0–1300 ft) | 1800–2900 m (5900–9500 ft) |
Distribution |
MI; MN; WI; MB; ON; QC
|
CO; NM; WY
|
Discussion | The name Aster longifolius Lamarck has been misapplied to this taxon. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Symphyotrichum porteri is the only western member of subsect. Porteriana; it grows in the foothills of the Rocky Mountains. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 20, p. 530. | FNA vol. 20, p. 513. |
Parent taxa | Asteraceae > tribe Astereae > Symphyotrichum > subg. Symphyotrichum > sect. Symphyotrichum | Asteraceae > tribe Astereae > Symphyotrichum > subg. Symphyotrichum > sect. Symphyotrichum |
Sibling taxa | ||
Synonyms | Aster robynsianus | Aster porteri, Aster ericoides var. strictus |
Name authority | (J. Rousseau) Brouillet & Labrecque: Phytologia 82: 138. (1997) | (A. Gray) G. L. Nesom: Phytologia 77: 289. (1995) |
Web links |