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amethyst aster, aster, hybrid aster

Habit Perennials, cespitose, 30–120 cm; with thick, woody, short-branched caudices at ends of fleshy rhizomes. Perennials, 40–100 cm, cespitose, eglandular; with cormoid, woody caudices.
Stems

1–5+, erect (light brown to grayish brown), densely hispidulo-hirsute.

5–10+, erect or arching (light to dark brown), proximally sparsely to moderately finely woolly-pilose (hairs spreading to ascending), more densely so distally.

Leaves

light green, thin to firm;

basal withering by flowering, sessile, blades oblanceolate, 10–40 × 3–10 mm, attenuate, margins usually entire, rarely remotely serrate, piloso-ciliate, apices obtuse, rounded to mucronulate, faces sparsely to moderately strigose;

proximal cauline sometimes persistent by flowering, sessile, blades linear or oblong to elliptic-oblanceolate, 40–60 × 3–10 mm, bases rounded or slightly clasping, margins entire, scabrous, apices acute to obtuse, faces ± copiously hirsute;

distal sessile, blades oblanceolate, 15–45 × 2–3(–4.5) mm, progressively reduced distally, bases cuneate, margins entire, apices acute, white-spine-tipped, faces sparsely strigose.

(grayish) soft;

basal withering by flowering, sessile, blades (1–3-nerved) elliptic-lanceolate, 20–40 × 10–20 mm, bases attenuate, margins usually entire, rarely remotely serrate, piloso-ciliate, apices acute to obtuse, faces silvery piloso-silky;

proximal cauline withering by flowering, sessile, blades oblanceolate, 20–30 × 4–8 mm, bases rounded, subclasping, margins entire, scabrous to silky-piloso-ciliate, apices acute to obtuse, cuspidate-mucronate, faces moderately strigillose;

distal sessile, blades lanceolate to narrowly ovate, 8–15 × 2.5–5 mm, reduced distally, bases cuneate, margins entire, apices acute, mucronate, faces moderately, finely lanoso-strigose.

Peduncles

hispid, bracts 1–3+, oblong-lanceolate, 3–5 mm, not grading into phyllaries.

densely hairy, bracts linear, grading into phyllaries.

Involucres

campanulate to hemispheric, 4–6 mm.

campanulate, 7–9 mm.

Ray florets

20–35;

corollas azure blue to violet or lavender, laminae 5–10 × 0.6–1.2 mm.

7–12;

corollas rose-purple, laminae 6–9 × 1–2 mm.

Disc florets

20–30+;

corollas light yellow turning pinkish to purple, 3–4 mm, tubes ca. 1/2 narrowly funnelform throats, lobes triangular, 0.5–0.7 mm, glabrous.

14–20;

corollas pink turning purple, 5–6 mm, tubes shorter than narrowly funnelform throats (thinly puberulent), lobes triangular, 0.3–0.5 mm.

Phyllaries

in 3–5 series, linear-lanceolate, ± unequal to subequal, bases ± indurate, margins hyaline proximally, outer distally hispido-scabrous, green zones diamond-shaped, restricted to distal 1/2–1/4, apices (outer) spreading to reflexed, acute, subspinulose, (inner) acuminate, purplish, faces (outer) scabroso-puberulent or strigose, eglandular, inner distally stipitate-glandular.

in 3–4 series, spreading to reflexed, linear, unequal, bases (tan) ± indurate, margins scarious proximally, green distally, green zones foliaceous, apices acute, faces moderately woolly-strigose.

Heads

in ample, leafy, paniculiform arrays, branches ascending, sometimes secund (heads often crowded).

radiate, in narrow, paniculiform (wand-shaped) to sometimes compact, racemiform arrays (1(–3) per branch).

Cypselae

dull purple or brown, obovoid, not compressed, 1.5–2 mm, 7–9-nerved, faces densely sericeous;

pappi tan to tawny, sometimes rose to violet-tinged, 3.5–5.5 mm.

fusiform-obovoid, not compressed, 2–3 mm, 6–8-nerved, faces densely strigose;

pappi tan to yellowish tan, (5.5–)6.5–8 mm.

2n

= 10.

= 8.

Symphyotrichum ×amethystinum

Symphyotrichum plumosum

Phenology Flowering Aug–Oct. Flowering Oct–Nov.
Habitat Fields, prairies, disturbed grounds Deep, dry to moist, sandy soils, pine flatwoods, pine-scrub oak woods, favored by fires and clearcuts
Elevation 200–400 m (700–1300 ft) 0–40 m (0–100 ft)
Distribution
from FNA
CO; CT; IA; IL; IN; KY; MA; MD; MN; MO; ND; NE; NJ; NY; PA; RI; VT; WA; WI; ON
[BONAP county map]
from FNA
FL
[BONAP county map]
Discussion

Symphyotrichum ×amethystinum is the F1 hybrid between S. ericoides and S. novae-angliae, encountered sometimes throughout the area where the two parental species co-occur. It is morphologically intermediate; it has non-spiny, sparsely stipitate-glandular phyllaries and rose-violet rays in mid-sized heads. Forma leucerythros Bemis and forma leucos Bemis have been described within this hybrid and may represent recombinants or normal population color variants.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Symphyotrichum plumosum is known only from Franklin County. It differs from S. concolor var. concolor in its long-acuminate, recurved to reflexed phyllaries. No intermediates with S. concolor were seen in the field.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 20, p. 497. FNA vol. 20, p. 493.
Parent taxa Asteraceae > tribe Astereae > Symphyotrichum > subg. Virgulus Asteraceae > tribe Astereae > Symphyotrichum > subg. Virgulus
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. urophyllum, S. walteri, S. welshii, S. yukonense
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. 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. urophyllum, S. walteri, S. welshii, S. yukonense, S. ×amethystinum
Synonyms Aster amethystinus, Virgulus ×amethystinus Aster plumosus, S. concolor var. plumosum
Name authority (Nuttall) G. L. Nesom: Phytologia 77: 294. (1995) (Small) Semple: in J. C. Semple et al., Cult. Native Asters Ontario, 134. (2002)
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