Symphyotrichum lanceolatum

Lance-leaved Aster or Panicled A. or White Panicled A., aster lancéolé

Symphyotrichum lanceolatum (Willd.) Nesom is the most widely distributed species in the genus occurring in 11 provinces and territories and Canada and all lower 48 states in the US (Brouillet et al. 2006; FNA), and it is introduced in Europe. The species has been the subject of multiple systematic studies on its cytogeography, ecology, and systematics (Semple 1979; Semple et al. 1983; Chmielewski & Semple 1983, 2001; Chmielewski 1991; Horsburgh et al. 2011). The species includes tetraploids 2n=32, pentaploids 2n=40, hexaploids 2n=48, septaploids 2n=56 and octaploids 2n=64 with some aneuploidy at the higher levels.

The species includes considerable variation in stem hair density, leaf shape, involucre height, outer phyllary length, and ray floret lamina color. Two subspecies are recognized; 1 eastern with 4 varieties and 1 western with 1 variety:

1. Outer phyllaries 2 / 3 + length of inner ones; heads usually subtended by large foliaceous bracts; cordilleras and prairies (subsp. hesperium)

Symphyotrichum lanceolatum var. hesperium

1. Outer phyllaries 1 / 3 – 2 / 3 length of inner ones; heads not usually subtended by large foliaceous bracts; prairies eastwards (subsp. lanceolatum)

2. Stems stout, moderately to densely short-woolly from bases; Great Lakes region to SE Manitoba

Symphyotrichum lanceolatum var. hirsuticaule

2. Stems stout to slender, glabrous or at most hairy in lines at bases

3. Heads congested on lateral branches of arrays; involucres 3–4 mm; midwestern United States, s Ontario, s Quebec

Symphyotrichum lanceolatum var. interior

    3. Heads not congested or congested only distally on lateral branches of arrays; involucres 3.6–5.6 mm (mostly longer than 4 mm)

       4. Leaves broadly oblanceolate, not much reduced in arrays; involucres usually 4–5.5 mm; rays white

Symphyotrichum lanceolatum var. latifolium

4. Leaves linear to oblanceolate, reduced in arrays; involucres 3.5–5(–6) mm; rays white to purplish

Symphyotrichum lanceolatum var. lanceolatum

Semple, J.C. 1979. The cytogeography of Aster lanceolatus (synonyms A. simplex and A. paniculatus) in Ontario with additional counts from populations in the United States. Can. J. Bot. 57: 397-402.

Semple, J.C., J.G. Chmielewski, K. Sankara Rao, and G. A. Allen. 1983. The cytogeography of Aster lanceolatus. II. A preliminary survey of the range including A. hesperius. Can. J. Bot. 61: 434-441.

Chmielewski, J.G., and J.C. Semple. 1983. The cytogeography of Aster lanceolatus. III. Cytoecology in southern Ontario. Can. J. Bot. 61:1879-1886.

Brousseau, H. & L. Brouillet. 1986. Cytogéographie de Aster lanceolatus Willd. au Québec. Ann. ACFAS 54: 62.

Semple, J. C. and J. G. Chmielewski. 1987. Revision of the Aster lanceolatus complex, including A. simplex and A. hesperius (Compositae: Astereae): A multivariate morphometric study. Canad. J. Bot. 65: 1047–1062.

Chmielewski, J.G. 1991. Comparison of resource allocation patterns among the cytotypes of experimentally cultivated Aster anceolatus (Asteraceae). Beitr. Biol Pflanzen 66: 421-432.

Chmielewski, J.G., and J.C. Semple. 2001. The Biology of Canadian weeds. 113. Symphyotrichum lanceolatum (Willd.) Nesom [Aster lanceolatus Willd.] and S. lateriflorum (L.) Löve & Löve [Aster lateriflorum (L.) Britt.]. Canad. J. Plant Sciences 81: 829-849.

Brouillet, L., J.C. Semple, G.A. Allen, K. Chambers and S. Sundberg. 2006. Symphyotrichum Nees. pp. 465-539. In Flora North America Editorial Committee, eds. Flora of North America. Vol. 20. Asteraceae, Part 2. Astereae and Senecioneae. Oxford University Press, New York.

Horsburgh, M., J.C. Semple and P.G. Kevan. 2011. Relative pollinator effectiveness of insect floral visitors to two sympatric species of wild aster – Symphyotrichum lanceolatum (Willd.) Nesom and Symphyotrichum lateriflorum (L.) Löve & Löve (Asteraceae: Astereae). Rhodora 113: 64-86.

Last revised 5 May 2021 by J.C. Semple