Willowleaf aster (Symphyotrichum praealtum) COSEWIC status assessment and status report chapter 3
Species information
Name and classification
Scientific name:
Symphyotrichum praealtum (Poir.) Nesom
Bibliographic citation:
Phytologia 77: 289. 1994.
Type specimen:
not seen, location uncertain
Synonyms:
- Aster praealtus Poir. Encyc. Suppl. 1: 493. 1810
- Aster salicifolius Ait., Hort. Kew. Ed. 1. 3: 203. 1789. non Juss. ex Lam.(1789), non Nees (1818), non Richardson (1823). TYPE: “Nat. North America, cult. Mr. P. Miller “ (Holotype: Hort. Kew, not seen).
- Aster rigidulus Desf., Cat. 122. 1815. non Nees (1818). TYPE: not seen.
- Aster obliquus Nees, Syn. Ast. 27. 1818. TYPE: not seen.
- Aster subasper Lindl. in Hook., Comp. Bot. Mag. 1: 97. 1835. Aster praealtus Poir. var. subasper (Lindl. in Hook.) Wieg., Rhodora 35: 24. 1933. Symphyotrichum praealtum (Poir.) Nesom var. subasperum (Lindl. in Hook.) Nesom, Phytologia 77: 290. 1994. TYPE: U.S.A. Missouri. St. Louis, 1831, Drummond 185 (Lectotype [Jones 1986]: K ! (Herb. Hook.); Isolectotype: P; possible Isolectotype: CGE !).
- Aster coerulescens DC, Prod. 5: 235. 1836. Aster salicifolius Lam. var. coerulescens (DC.) A. Gray, Synop. Fl. N. Amer. 1,2: 188. 1884. Aster praealtus Poir. var. coerulescens (DC.) A.G. Jones, Phytologia 55: 383. 1984. TYPE: U.S.A. Texas. Cammancheros Oriental, Dec. 1828, Berlandier 1885 (Holotype: G-DC !; Isotypes: BM !, G,G-DC, GH !, K !, MO, P(2) !).
- Aster carneus Nees, Syn. Ast. 26. 1818. TYPE: not seen.
- Aster carneus Torr. & Gray, Fl. N. Amer. 2: 133. 1841. in part. [attributed to Nees in protologue].
Common name:
Willowleaf Aster; willow aster
Family name:
Asteraceae, Compositae
Common family name:
Sunflower family, Aster family
Major plant group:
Angiosperm (dicot flowering plant)
Willowleaf aster, prior to acceptance of Nesom’s name change, was commonly recognized as Aster praealtus Poir. Two varieties of willowleaf aster are recognized by Semple (1996); S. praealtum var. praealtum occurs widely throughout the central United States and extends into Canada whereas var. angustior is an eastern variety restricted mainly to the Appalachians in the USA and does not extend into Canada.
Description
The following comprehensive technical description is taken from Semple et al. (1996):
Herbaceous perennials from herbaceous rhizomatous rootstocks. Stems erect, 1-15 dm tall, glabrate, somewhat glaucous, sparsely to moderately pubescent in lines in capitulescence. Lower stem leaves oblanceolate, sessile, serrate, deciduous by flowering. Upper stem leaves linear to elliptic-lanceolate, sessile, margins entire to sparsely serrate-ciliate, upper surface glabrate to sparsely short-scabrous, cuticle thick, undersurface glabrate, veins pronounced, most alveolae isodiametric; branch leaves similar, reduced. Capitulescence paniculiform, leafy, few to many heads. Peduncles moderately to densely pubescent; bracts many, foliaceous, narrowly elliptic to lanceolate. Involucres campanulate-turbinate, 4.0–6.0 mm high. Phyllaries in 4-6 strongly graduated series, glab rate, inner surface sparsely pubescent, diamond-shaped chlorophyllous zone small. Rays 20-35, 5-9 mm long, 1-1.7 mm wide, pale blue-violet. Disc corollas 20-30, 4-6 mm long, yellow becoming purple, somewhat ampliate, lobes 0.5-1.0 mm long. Achenes compressed obconic, 1(-2) ribs per side, sparsely strigose; single pappus whorl about equal to disc corolla. Chromosome numbers: 2n=32, [64]; several populations sampled in Ontario.
Willowleaf aster is distinguished by its smooth and somewhat waxy stems, its pale violet rays, and its leaves with pronounced veins on the lower surface which enclose isodiametric alveolae (Figure 1).
Figure 1. Morphology of willowleaf aster (Symphyotrichum praealtum var. praealtum) from Semple et al. (1996). A. Habit. B. Upper stem leaf with upper surface on left and lower surface on right. C. Branch leaf detail of mid portion enlarged to show alveolae on the underside. D. Head with only some florets drawn. E. Mid series phyllary with chlorophyllous zone dark. F. Mature disc floret achene with corolla attached.
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