Herbs , annual. Leaves basal, simple, tapering to filiform base. Leaf blade linear or very narrowly oblanceolate, margins entire. Inflorescences terminal, solitary flowers; bracts absent. Flowers bisexual, radially symmetric; sepals not persistent in fruit, (3-)5(-8), green or with scarious margins, spurred, oblong to elliptic, lanceolate, or oblanceolate, 1.5-4 mm; petals 0-5, distinct, white, plane, linear to very narrowly spatulate, long-clawed, 1-2.5 mm; nectary present; stamens 5-25; filaments filiform; staminodes absent between stamens and pistils; pistils 10-400, simple; ovule 1 per pistil; style persistent. Fruits achenes, aggregate, sessile, prismatic, exposed face forming plane outer surface, sides faceted or curved by compression against adjacent achenes; sides not veined; beak terminal, straight, 0.05-1.8 mm. x =8. Flowers of Myosurus are unique in the family in that the receptacle continues to elongate and, in some species, to initiate new ovaries after the flowers open and pollen is shed (D.E. Stone 1959). Mature fruits are crucial to accurate identification of most North American species of Myosurus .
Fls regular; sep 5, spurred at the base; pet 5, or none, long-clawed, the scarcely dilated blade nectariferous at the summit; stamens 5-20; pistils numerous, on a long, slender receptacle; achenes quadrate or hexagonal with a large basal scar, areolate on the sides, truncate and ridged on the summit; small annuals with linear lvs and 1- fld scapes. 6-7, widespread.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.