50c. Symphyotrichum lanceolatum (Willdenow) G. L. Nesom var. interior (Wiegand) G. L. Nesom, Phytologia. 77: 284. 1995.
Aster interior Wiegand, Rhodora 35: 35. 1933; A. lanceolatus Willdenow subsp. interior (Wiegand) A. G. Jones; A. simplex Willdenow var. interior (Wiegand) Cronquist
Stems usually slender, sometimes stout , glabrous or hairy in lines. Leaf blades linear-lanceolate to lanceolate, distal cauline margins entire . Heads congested on lateral branches of arrays, often developing on short peduncles along most of the branch, usually not subtended by large foliaceous bracts. Involucres 3–4 mm. Phyllaries: outer 1.8–3.4 × ca. 0.4, inner 3.5–3.7 × 0.4–0.5 mm, outer 1 / 3 – 2 / 3 length of inner. Ray florets 22–24; corollas white, laminae 3.9–5.8 mm. Disc florets 20–23; corollas 2.8–3.1 mm, limbs 1.6–1.8 mm, lobes 0.5–0.7 mm. Cypselae 0.6–0.8 mm; pappi 2.9–3.3 mm. 2n = 48, 64.
Flowering Jul–Oct. Bottomlands, along streams; 10–400 m; Ont., Que.; Ark., Ill., Ind., Iowa, Kans., Ky., Mich., Mo., Nebr., N.Y., Ohio, Okla., Pa., Vt.