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pygmy aster

Porter's or smooth white aster, smooth white aster

Habit Perennials 1.5–15 cm, cespitose; with short, branched caudices, long-rhizomatous (both wiry). Perennials, 10–50 cm, cespitose; usually with branched caudices, sometimes long-rhizomatous.
Stems

1–10+, decumbent to ascending (purple), sparsely or densely villous to woolly distally.

1–4+, ascending to erect (straight), glabrous.

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 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

densely villous to lanate distally, bracts 0.

0.2–2.8 cm, bracteate, glabrous, bracts 1–3, linear to linear-lanceolate.

Involucres

hemispherico-campanulate, 9–12.5 mm.

campanulate to cylindro-campanulate, 3.6–5(–6) mm.

Ray florets

16–28;

corollas purple to violet, laminae 12–18 × 2–3.2 mm.

(12–)20–34(–42);

corollas usually white, seldom pinkish, laminae 6.8–12 × 0.7–1.8 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).

(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 (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, 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

borne singly.

in paniculiform arrays, branches ascending, ± densely leafy with narrow branch leaves.

Cypselae

fusiform to cylindro-obconic, ± compressed, [size unknown], 4–7-nerved (faint), faces ± densely strigillose;

pappi whitish to yellowish, 5–7.2 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

= 16.

Symphyotrichum pygmaeum

Symphyotrichum porteri

Phenology Flowering summer. Flowering late Jul–Sep.
Habitat Open, active, moist sand dunes, sandy or silty stream banks and terraces, usually cyclically disturbed gravelly tundra and tundra slopes Lower montane
Elevation 0–200+ m (0–700+ ft) 1800–2900 m (5900–9500 ft)
Distribution
from FNA
AK; NT; NU
[BONAP county map]
from FNA
CO; NM; WY
[WildflowerSearch map]
[BONAP county map]
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.)

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. 485. FNA vol. 20, p. 513.
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. 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. 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. 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. ontarionis, S. oolentangiense, S. parviceps, S. patens, S. phlogifolium, S. pilosum, S. plumosum, 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
Synonyms Aster pygmaeus, Aster sibiricus subsp. pygmaeus, Aster sibiricus var. pygmaeus, Eurybia pygmaea Aster porteri, Aster ericoides var. strictus
Name authority (Lindley) Brouillet & S. Selliah: Sida 21: 1635. (2005) (A. Gray) G. L. Nesom: Phytologia 77: 289. (1995)
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