Symphyotrichum lanceolatum var. hesperium

(A. Gray) G. L. Nesom

Phytologia 77: 284. 1995.

Basionym: Aster hesperius A. Gray in A. Gray et al., Syn. Fl. N. Amer. 1(2): 192. 1884
Synonyms: Aster coerulescens var. wootonii (Greene) Wiegand Aster durus Lunell Aster fluvialis Osterhout Aster hesperius var. wootonii Greene Aster lanceolatus subsp. hesperius (A. Gray) Semple & Chmielewski Aster lautus Rydberg Aster osterhoutii (Greene) Greene Aster wootonii (A. Gray) Á. Löve and D. Löve Symphyotrichum hesperium
Treatment appears in FNA Volume 20. Treatment on page 520. Mentioned on page 519.

Stems stout, glabrous or at most hairy in lines. Leaf blades linear-lanceolate or -oblanceolate, proximal cauline margins shallowly serrate, mid to distal entire. Heads 1–100+, borne singly or congested at ends of lateral branches, usually subtended by large foliaceous bracts. Involucres 4–7.2 mm. Phyllaries: outer 2.6–6.3 × 0.4–1 mm, inner 4–7.4 × 0.2–1.1 mm, outer 2/3+ length of inner. Ray florets 18–45; corollas usually pale to dark purplish blue, sometimes white, laminae 4.2–10.1 mm. Disc florets 18–52; corollas 3.3–5.7 mm, limbs 2–3.8 mm, lobes 0.5–1.1 mm. Cypselae 0.7–2.7; pappi 3.7–6.4 mm. 2n = 64.

Phenology: Flowering Jul–Oct.
Habitat: Along streams and banks in prairies, wet meadows, open conifer forests in montane zone, often calcareous soils, roadside ditches
Elevation: 10–2700 m



Alta., B.C., Man., N.W.T., Ont., Que., Sask., Ariz., Calif., Colo., Idaho, Iowa, Kans., Minn., Mont., Nebr., Nev., N.Mex., N.Dak., Okla., Oreg., S.Dak., Tex., Utah, Wash., Wis., Wyo., Mexico (Baja California, Chihuahua, Sonora).


Variety hesperium is present at the northeastern limit of its range in Quebec only on the clays of the southern James Bay; a report of introduction in the Gatineau area is attributable to Symphyotrichum robynsianum. In north-central Ontario, it is found mainly in areas of clay deposits or in calcareous stream valleys, but not in the Clay Belt, reaching the southern James Bay. This variety has been treated mostly as a distinct species in floras. Character ranges overlap considerably with var. lanceolatum, and it is often difficult to distinguish the two entities where their distributions overlap. In areas of sympatry, the two taxa hybridize to form septaploid plants (2n = 56).

Selected References


Lower Taxa

Luc Brouillet +, John C. Semple +, Geraldine A. Allen +, Kenton L. Chambers +  and Scott D. Sundberg† +
(A. Gray) G. L. Nesom +
Aster hesperius +
Alta. +, B.C. +, Man. +, N.W.T. +, Ont. +, Que. +, Sask. +, Ariz. +, Calif. +, Colo. +, Idaho +, Iowa +, Kans. +, Minn. +, Mont. +, Nebr. +, Nev. +, N.Mex. +, N.Dak. +, Okla. +, Oreg. +, S.Dak. +, Tex. +, Utah +, Wash. +, Wis. +, Wyo. +, Mexico (Baja California +, Chihuahua +  and Sonora). +
10–2700 m +
Along streams and banks in prairies, wet meadows, open conifer forests in montane zone, often calcareous soils, roadside ditches +
Flowering Jul–Oct. +
Illustrated +
Aster coerulescens var. wootonii +, Aster durus +, Aster fluvialis +, Aster hesperius var. wootonii +, Aster lanceolatus subsp. hesperius +, Aster lautus +, Aster osterhoutii +, Aster wootonii +  and Symphyotrichum hesperium +
Symphyotrichum lanceolatum var. hesperium +
Symphyotrichum lanceolatum +
variety +