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arrow-leaf American-aster, white arrowleaf aster, white arrowleaf or arrowleaf aster

Habit Perennials, 40–120(–200) cm, cespitose; short-rhizomatous or with stout, branched caudices.
Stems

1–5+, erect (straight to slightly flexuous, brittle, sometimes stout), proximally glabrous or glabrate, distally sparsely pilose.

Leaves

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

0.3–2 cm, sparsely pilosulous to glabrate, bracts many, ascending, linear to subulate, 2–4 mm, grading into phyllaries.

Involucres

cylindric, (4–)4.5–6(–7) mm.

Ray florets

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

(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 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

(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

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.

Symphyotrichum urophyllum

Phenology Flowering Aug–Oct.
Habitat 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 40–300+ m (100–1000+ ft)
Distribution
from FNA
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

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. 506.
Parent taxa 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. 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. walteri, S. welshii, S. yukonense, S. ×amethystinum
Synonyms Aster urophyllus, Aster sagittifolius var. dissitiflorus
Name authority (Lindley ex de Candolle) G. L. Nesom: Phytologia 77: 294. (1995)
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