Herbs, annual, rarely biennial, cespitose or solitary, 10--100 cm. Stems compact. Leaves erect or ascending in narrow fans, 5--60 cm; sheaths straw-colored, light green, or brown, smooth; blade green, linear, flattened, 2--5(--15) mm wide, smooth, margins smooth or papillate. Inflorescences: scape sheaths exceeded by principal leaves; scapes linear, terete, distally oval, (0.5--)1--1.5(--2) mm wide, smooth, 1--2-ribbed, ribs papillate; spikes ovoid to ellipsoid or cylindro-lanceoloid, 7--15(--25) mm, apex acute; fertile bracts 5--7 mm, margins entire, apex rounded. Flowers: lateral sepals included, slightly curved, 5--7 mm, keel scarious, lacerate, thin; petals unfolding in morning, blade obtriangular, 3 mm; staminodes bearded. Seeds translucent, ellipsoid, 0.4--0.5 mm, faintly ribbed. 2n = 18. Flowering summer--fall (all year south). Moist sands, sandy peats of savannas, flatwoods, swales, shores, ditches, and roadsides, particularly in disturbed situations; 0--350 m; Ala., Ark., Del., Fla., Ga., La., Md., Miss., N.J., N.C., Okla., S.C., Tenn., Tex., Va.; Mexico; West Indies; Central America; South America. The widest-ranging of all New World Xyrids and the most ample ecologically, Xyris jupicai is a frequent invader of disturbed or fallow open wetlands within its extensive range. In the southeastern United States it frequently shares habitat with two other species of its complex, namely X. difformis var. difformis and X. laxifolia. It differs from both in its lack of red pigmentation, from X. difformis by its more erect leaves and narrower, less prominently ribbed scapes, and from X. laxifolia by its narrower leaves and scapes, shorter, narrower, paler spikes, and translucent (rather than mealy), shorter seeds. Nonetheless, some difficult 'calls' arise since all three flower at the same time and occasional chance hybrids do form.
Short-lived, often annual; lvs linear, mostly 10-60 cm נ2-5 mm, ascending, smooth, lustrous yellow-green, pale (not anthocyanic) at the dilated, soft, thin, keeled base; scapes 2-8 dm, terete and finely many-ridged below, becoming flattened (but narrow) and usually 1- or 2-edged above; spikes 0.5-1.5 cm at maturity, narrowly ovoid to oblong, blunt; lateral sep shortly included, the broad keel lacerate for 1/2-2/3 its length; pet-blades cuneate, 3 mm, yellow, unfolding in the morning; seeds 0.5 mm, faintly ribbed; 2n=18. Wet, sunny, disturbed sites, often weedy; coastal plain from N.J. to Fla., Tex., and trop. Amer., perhaps only intr. in U.S. Early summer-fall.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.