Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Genus Description - Spikelets mostly in simple or compound, often umbelliform cymes (or virtually a head) forming a terminal infl subtended by 2–several slender, ± lf-like invol bracts; scales spirally imbricate; fls perfect; perianth none; stamens 1–3; style trifid, the unbranched portion smooth, the base enlarged and usually persistent on the trigonous achene as a tubercle (minute in our spp.); radicle basal; herbs with mostly basal, filiform to narrowly linear lvs, the sheath long-ciliate or fimbriate at the top. 80+, mainly trop. B. stenophylla (Elliott) C. B. Clarke, a coastal plain sp., closely approaches our range in N.C. and may be sought in se. Va. The stems have a single dense terminal cluster of virtually sessile spikelets, subtended by elongate, setaceous invol bracts.