T: [Citation: "Ohio to Michigan, Illinois and southward". The citation is connected with a shortly later publication, G.Engelmann, Trans. Acad. Sci. St. Louis 2: 467 (Apr 1868), with numerous syntypes cited. Two of them were distributed as numbered exsiccates as follows.] USA, Illinois, Athens, E.Hall [G.Engelmann, Herb. Junc. Bor.-Amer. Norm.] 63; syn: MO, NY, PR, S; Canada, Ontario, Sandwich, J.M.Bigelow [G.Engelmann, Herb. Junc. Bor.-Amer. Norm.] 64; syn: MO, NY, PR, S.
Perennials, (30–) 45–80 (–90) cm tall. Rhizome long-creeping, 3–4 mm in diam., tuberous. Cataphylls absent (rarely 1, lax, stramineous, acute); basal leaves 1–2, 3–50 cm. Cauline leaves 2–4, 3–50 cm long, terete, perfectly septate (septa not distinct externally, only in dry condition), unitubular, usually 1.0–1.3 mm in diam.; tip acute; auricles 0.5–3.5 mm long, rounded, scarious. Lower bract leaf-like, terete, 1.5–3 cm long, shorter than the inflorescence, erect; other bracts green, lanceolate, 9–12 mm long. Inflorescence decompound, of (1–) 2–10 (–20) heads, 1–4 (–10) cm tall, with ascending branches; heads globose, of echinate appearance, 30–100-flowered, 8–10 mm in diam.; peduncles usually suberect, short. Tepals unequal, linear-lanceolate, with apex subulate, green to stramineous, often red-tinted, acuminate; inner tepals 2–3.2 mm long; outer tepals 2.5–3.8 mm long. Stamens 3, not exserted; anthers 0.3–0.4 mm long; filaments 0.7–0.9 mm long; style 0.1–0.3 mm long; stigmas 0.4–0.9 mm long. Capsules unilocular, obconic or narrowly ovoid, obtuse to subacute, 1.7–2.7 mm long, pale brown to light castaneous-brown, shorter than perianth. Seeds obliquely ellipsoid, apiculate, 0.3–0.5 × c. 0.2 mm, irregularly reticulate; appendages absent. 2n = 44, fide N.A.Harriman & D.Redmond, Rhodora 78: 734 (1976).