Herbs, annual or perennial, often cespitose, rosulate. Roots: larger roots unbranched, pale, septate, thickened, spongy. Stems rarely sparingly branched, short or elongate. Leaves many ranked in flat or high spiral; blade basally pale, distally greener, linear-attenuate or triangular-acuminate, lingulate, narrowing gradually or abruptly from base, base noticeably lacunate, less distinctly so distally. Inflorescences: scape sheaths tubular, orifice oblique (often 2--3-cleft); scapes 1--several per rosette, glabrous; heads pale to dark, white, gray, or gray-brown, hemispheric to globose or short-cylindric; receptacle hairy or glabrous; involucral bracts obscured or not obscured by inflorescence, pale to dark, chaffy or scarious; receptacular bracts narrower, thinner than involucral bracts, often scarious. Flowers mostly with staminate and pistillate on same plants, 2--3-merous; sepals 2(--3), adnate to stipelike base, boat-shaped, scarious, apex often covered with multicellular hairs, hairs mealy white or translucent, frequently club-shaped; petals 2(--3), narrower, shorter than sepals, apex hairy, hairs club-shaped, glands adaxial, subapical, dark, rarely pale. Staminate flowers: androphore apically dilated stalk; petals separated from sepals by androphore, diverging as lobes from apex; stamens 3--4 or 6, 2--3 alternating with petals; apex of staminal column with 2--3 glands, glands unappendaged; filaments arising from androphore rim; anthers 2-locular, 4-sporangiate, dorsifixed, usually versatile, well exserted at anthesis, jet black (except in E. cinereum). Pistillate flowers: gynophore separating petals from sepals, stipelike; pistil 2(--3)-carpellate; style 1, unappendaged, style branches 2(--3).
Fls each subtended by a small bract, dimerous in our spp., the sep 2, distinct or connate, the pet 2, each with a nectariferous gland just within the tip, the ovary bilocular and the style bifid; staminate fls with an androphore; stamens bicyclic (4 in our spp.), exsert at anthesis; anthers with 2 pollen-sacs, black at maturity in our spp.; ovary on a gynophore which also bears the pet; lvs with evident lacunar tissue especially toward the base; roots fleshy-fibrous, septate, pale, unbranched. 400, mainly warm reg. The hairs of the receptacle, mentioned in the key below, are very slender and much elongate, in contrast to the thick short hairs of the perianth and receptacular bracts.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.