Symphyotrichum ×amethystinum

(Nuttall) G. L. Nesom

Phytologia 77: 294. 1995.

Common names: Amethyst aster
Basionym: Aster amethystinus Nuttall Trans. Amer. Philos. Soc., n. s. 7: 294. 1840
Synonyms: Virgulus ×amethystinus (Nuttall) Reveal & Keener
Treatment appears in FNA Volume 20. Treatment on page 497. Mentioned on page 471, 472, 483, 487, 488, 498.

Perennials, cespitose, 30–120 cm; with thick, woody, short-branched caudices at ends of fleshy rhizomes. Stems 1–5+, erect (light-brown to grayish brown), densely hispidulo-hirsute. 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. Heads in ample, leafy, paniculiform arrays, branches ascending, sometimes secund (heads often crowded). Peduncles hispid, bracts 1–3+, oblong-lanceolate, 3–5 mm, not grading into phyllaries. Involucres campanulate to hemispheric, 4–6 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. Ray-florets 20–35; corollas azure blue to violet or lavender, laminae 5–10 × 0.6–1.2 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. 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. 2n = 10.


Phenology: Flowering Aug–Oct.
Habitat: Fields, prairies, disturbed grounds
Elevation: 200–400 m

Distribution

V20-1116-distribution-map.gif

Ont., Colo., Conn., Ill., Ind., Iowa, Ky., Md., Mass., Minn., Mo., Nebr., N.J., N.Y., N.Dak., Pa., R.I., Vt., Wash., Wis.

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.

Selected References

None.

Lower Taxa

None.

"thick" is not a number."thin" is not a number.

not tailed +, rounded +  and obtuse +
white-spine-tipped +  and sessile +
entire +  and serrate +
distinct +
1 cm10 mm <br />0.01 m <br /> (4 cm40 mm <br />0.04 m <br />) +
hirsute +  and strigose +
subequal +
scarious +
3mm +  and 10mm +
usually triangular +  and linear +
usually deltate +  and lanceolate +
paniculiform +  and leafy +
indeterminate +  and determinate +
Luc Brouillet +, John C. Semple +, Geraldine A. Allen +, Kenton L. Chambers +  and Scott D. Sundberg† +
(Nuttall) G. L. Nesom +
4 cm40 mm <br />0.04 m <br /> (6 cm60 mm <br />0.06 m <br />) +
cuneate +, acute +  and obtuse +
indurate +
3mm;10mm +
Aster amethystinus +
0.3 cm3 mm <br />0.003 m <br /> (0.45 cm4.5 mm <br />0.0045 m <br />) +
1.5 cm15 mm <br />0.015 m <br /> (4.5 cm45 mm <br />0.045 m <br />) +
oblanceolate;acute;obtuse +
reduced +
2mm;3mm +
rugulose +  and muricate +
oblong-lanceolate +
barbellulate +  and barbellate +
short-branched +
Amethyst aster +
not 2-lipped +  and actinomorphic +
light yellow turning pinkish to purple +, azure blue +  and violet or lavender +
at maturity , more or less ampliate , tubes usually shorter +
0.3 cm3 mm <br />0.003 m <br /> (0.4 cm4 mm <br />0.004 m <br />) +
beaked +, 2-ribbed +  and 5-ribbed +
brown +, purple +  and dull +
not compressed +  and obovoid +
fertile +  and bisexual +
fertile +  and bisexual +
Ont. +, Colo. +, Conn. +, Ill. +, Ind. +, Iowa +, Ky. +, Md. +, Mass. +, Minn. +, Mo. +, Nebr. +, N.J. +, N.Y. +, N.Dak. +, Pa. +, R.I. +, Vt. +, Wash. +  and Wis. +
200–400 m +
eglandular +  and sessile +
entire +  and serrate +
1 cm10 mm <br />0.01 m <br /> (4 cm40 mm <br />0.04 m <br />) +
sericeous +, strigose +, scabroso-puberulent +  and hirsute +
acute;obtuse +
0.3 cm3 mm <br />0.003 m <br /> (1 cm10 mm <br />0.01 m <br />) +
pistillate +, staminate +  and neuter +
winged +  and beaked +
dispersed +
Fields, prairies, disturbed grounds +
disciform +  and radiate +
indeterminate +
heterogamous +  and homogamous +
each +  and sessile +
stipitate-glandular +
0.4 cm4 mm <br />0.004 m <br /> (2.2 cm22 mm <br />0.022 m <br />) +
campanulate;hemispheric +
0.4 cm4 mm <br />0.004 m <br /> (0.6 cm6 mm <br />0.006 m <br />) +
2.4 cm24 mm <br />0.024 m <br /> (2.5 cm25 mm <br />0.025 m <br />) +
0.6mm;1.2mm +
sessile +  and petiolate +
light green +
cauline +  and basal +
decurrent +
triangular +
entire +  and serrate +
10mm;40mm +
hirsute +  and strigose +
acute +  and obtuse +
3mm +  and 10mm +
2-carpellate +
rose +  and violet-tinged +
persistent +
25 +  and 40 +
0.35 cm3.5 mm <br />0.0035 m <br /> (0.55 cm5.5 mm <br />0.0055 m <br />) +
Flowering Aug–Oct. +
linear-lanceolate +
less unequal +  and subequal +
styliferous +, neuter +  and pistillate +
bearing subulate enations +, hairy +  and bristly +
flat;slightly convex +
exalbuminous +
branched +  and simple +
1 +  and 5 +
appendaged +  and truncate +
papillate +  and smooth +
Virgulus ×amethystinus +
Symphyotrichum ×amethystinum +
Symphyotrichum subg. Virgulus +
species +
at maturity , more or less ampliate , tubes usually shorter +
ampliate +
with cormoid caudices +  and rhizomatous +
stipitate-glandular +
30 cm300 mm <br />0.3 m <br /> (120 cm1,200 mm <br />1.2 m <br />) +
tree +, shrub +  and subshrub +
subspinulose +
purplish +  and green +
acuminate +, acute +  and diamond--shaped +