Symphyotrichum pygmaeum |
Symphyotrichum urophyllum |
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pygmy aster |
arrow-leaf American-aster, white arrowleaf aster, white arrowleaf or arrowleaf aster |
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Habit | Perennials 1.5–15 cm, cespitose; with short, branched caudices, long-rhizomatous (both wiry). | Perennials, 40–120(–200) cm, cespitose; short-rhizomatous or with stout, branched caudices. |
Stems | 1–10+, decumbent to ascending (purple), sparsely or densely villous to woolly distally. |
1–5+, erect (straight to slightly flexuous, brittle, sometimes stout), proximally glabrous or glabrate, distally sparsely pilose. |
Leaves | firm, margins usually entire, sometimes remotely pauci-serrulate, sparsely villoso-ciliate, apices obtuse to acute, sometimes mucronate; basal often withering by flowering, petiolate (petioles widely winged, sheathing), blades spatulate, 5–19 × 2–4 mm, bases attenuate, apices rounded, faces glabrous or sparsely villous proximally; proximal sessile, blades lanceolate to oblong-lanceolate or (sometimes) -spatulate, 30–50 × 3–10 mm, bases ± clasping, apices obtuse to acute, faces glabrous or sparsely villous; distal sessile, blades lanceolate to oblong, 13–19 × 2–4.5 mm, bases clasping to cuneate, apices acute to obtuse, faces sparsely woolly, sometimes sparsely stipitate-glandular. |
thin, margins usually shallowly, sometimes deeply serrate, rarely entire (distal), (piloso- to strigoso-)ciliate to scabrous (distal), apices mucronate, abaxial faces moderately pilose, ± densely so on midveins, adaxial glabrate to sparsely pilose or scabrous; basal usually withering by flowering, sometimes persistent, long-petiolate (5–15 cm, petioles not or narrowly winged, sheathing), blades ovate to lance-ovate or lanceolate, 25–120 × 15–50 mm, bases usually shallowly, sometimes deeply, cordate to truncate or rounded, apices acute, sometimes rounded; proximal cauline sometimes deciduous at flowering, winged-petiolate (petioles distally usually broader-winged, clasping), blades ovate to lanceolate, 50–120 × 20–50 mm, gradually reduced distally, bases usually truncate or rounded to attenuate, sometimes cordate, apices usually acute or acuminate, sometimes nearly caudate; distal ± shortly winged-petiolate or sessile, blades lance-ovate or lanceolate to linear-lanceolate, 10–100 × 1–25 mm, reduced distally, bases attenuate to cuneate, margins entire to subentire, scabrous, apices acuminate to subcaudate. |
Peduncles | densely villous to lanate distally, bracts 0. |
0.3–2 cm, sparsely pilosulous to glabrate, bracts many, ascending, linear to subulate, 2–4 mm, grading into phyllaries. |
Involucres | hemispherico-campanulate, 9–12.5 mm. |
cylindric, (4–)4.5–6(–7) mm. |
Ray florets | 16–28; corollas purple to violet, laminae 12–18 × 2–3.2 mm. |
8–15(–20); corollas mostly white to pale pink or lilac or light blue, laminae 4.5–8(–10) × 0.8–1.5 mm. |
Disc florets | 53–55; corollas yellow, 5.6–6.5 mm, throats funnelform, lobes triangular, 0.5–0.8 mm (red or white clavate-hairy). |
(8–)10–15(–20); corollas whitish to cream becoming pink, (3.5–)4–5 mm, tubes shorter than funnelform throats (with hairs), lobes lanceolate, 0.4–0.7 mm. |
Phyllaries | in 3–4 series (dark purple), lance-oblong or oblong (outer) to linear-lanceolate or sometimes linear (inner), subequal, outer ± herbaceous, bases not indurate, margins herbaceous (outer) to narrowly scarious and erose proximally (inner), strongly purple, villoso-ciliate in green portion, green zones (inner) 1/2–2/3 of distal portions, apices acute to acuminate, inner sometimes apiculate, appressed to loose and squarrose (particularly outer), faces woolly to densely villous, sparsely to moderately stipitate-glandular. |
in 4–6 series, appressed or recurved-spreading, subulate (outer) to linear-lanceolate (inner), unequal, bases indurate 1/3–1/2+, margins scarious, hyaline, erose, sparsely ciliolate (mostly distally), green zones linear-lanceolate (outer) to linear (inner), apices long-acuminate to caudate, recurved, hyaline-mucronate to aristate, tips often purple, faces glabrous. |
Heads | borne singly. |
(crowded) in dense, elongate, paniculiform arrays, branches stiffly ascending to erect (sometimes arched when long, peduncles then often secund), usually racemiform, sometimes paniculiform, leafy. |
Cypselae | fusiform to cylindro-obconic, ± compressed, [size unknown], 4–7-nerved (faint), faces ± densely strigillose; pappi whitish to yellowish, 5–7.2 mm. |
tan to brown or dull purple (nerves stramineous), obovoid, ± compressed, 1.8–2.5 mm, 4–6-nerved, faces glabrous or glabrate or very sparsely strigillose; pappi white or rose-tinged, 3–4 mm. |
2n | = 16. |
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Symphyotrichum pygmaeum |
Symphyotrichum urophyllum |
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Phenology | Flowering summer. | Flowering Aug–Oct. |
Habitat | Open, active, moist sand dunes, sandy or silty stream banks and terraces, usually cyclically disturbed gravelly tundra and tundra slopes | Open, dry or mesic, sandy or loamy, sometimes rocky soils, limestone pavements, glades, ravines, open oak, sassafras, aspen, or pine woods, edges of woods, moist or dry, rocky bluffs, savanna, wooded banks, stabilized dunes, fields, roadsides, hedgerows, railroads |
Elevation | 0–200+ m (0–700+ ft) | 40–300+ m (100–1000+ ft) |
Distribution |
AK; NT; NU |
AL; AR; FL; GA; IA; IL; IN; KS; KY; MA; MD; ME; MI; MN; MO; MS; NC; ND; NE; NJ; NY; OH; OK; PA; SC; TN; VA; VT; WI; WV; ON
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Discussion | Of conservation concern. Symphyotrichum pygmaeum has long been included within or associated with Eurybia sibirica. Though similar in appearance, the two species can be distinguished by the glands present on S. pygmaeum on the distal leaves and phyllaries. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
The name Aster sagittifolius Wedemeyer ex Willdenow has been misapplied to this taxon; our interpretation of the type of this entity concords with that of A. G. Jones (1980), i.e., that it is conspecific with the type of Symphyotrichum cordifolium or a garden hybrid involving the latter. Aster sagittifolius forma hirtellus (Lindley) Shinners is not recognized here. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 20, p. 485. | FNA vol. 20, p. 506. |
Parent taxa | ||
Sibling taxa | ||
Synonyms | Aster pygmaeus, Aster sibiricus subsp. pygmaeus, Aster sibiricus var. pygmaeus, Eurybia pygmaea | Aster urophyllus, Aster sagittifolius var. dissitiflorus |
Name authority | (Lindley) Brouillet & S. Selliah: Sida 21: 1635. (2005) | (Lindley ex de Candolle) G. L. Nesom: Phytologia 77: 294. (1995) |
Web links |