Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Genus Description - Fls perfect; tep 6, uniform in color but often somewhat unlike in shape or size, generally withering and persistent below the fr; stamens 6, often adnate to the base of the tep, the filaments of the epipetalous series often wider, or strongly flattened, or variously toothed; anthers short, introrse; ovules 1 or 2 per locule; capsule short, ovoid to globose or obovoid, 3-lobed, loculicidal; seeds black; herbs from a coated bulb, with a strong odor of onion or garlic, the lvs usually narrow, basal or on the lower part of the stem, the scape- like stem erect, terminated by a determinate umbel subtended by 1–3 bracts; fls white to pink or purple, sometimes replaced by sessile bulblets. 500, N. Hemisphere.