Herbs, perennial, cespitose, 50--150 cm. Stems compact. Leaves ascending in narrow fans, (19--)30--50(--60) cm; sheaths pinkish or pale red, soft, smooth; blade pale green proximally, distally deep lustrous green, linear, flattened, plane, 5--15 mm wide, margins smooth. Inflorescences: scape sheaths exceeded by leaves; scapes linear, straight, distally slightly compressed, 1--2 mm wide, smooth, 2-ribbed; spikes ovoid to ellipsoid or cylindric, 10--20(--25) mm, apex usually blunt; fertile bracts 5--8 mm, margins entire, apex rounded. Flowers: lateral sepals slightly to conspicuously exserted, slightly curved, 6--8 mm, keel scarious, apex not red, broad, thin, lacerate; petals unfolding in afternoon, blade obovate, 5--6 mm; staminodes bearded. Seeds translucent, narrowly ellipsoid to ovoid, (0.6--)0.7(--0.8 mm), irregularly ridged and cross-ridged. 2n = 18. Flowering summer--fall. Sandy or peaty shallows and shores of ponds and sluggish acidic streams; 0--100 m; Ala., Conn., Del., Fla., Ga., La., Maine, Md., Mass., Miss., N.H., N.J., N.Y., N.C., R.I., S.C., Tex.; West Indies (Cuba); Mexico (Tabasco); West Indies (Cuba); Central America (Belize, Honduras, Nicaragua). Although no specimens were seen for Virginia, Xyris smalliana is to be expected there.