Plants slender, 18–35 cm. Bulbs ca. 10 mm diam. Stems simple, rarely 1-branched. Leaves usually 3–4, basal leaves (0–)1–2; blade linear, ± reaching base of rhipidia, proximalmost cauline leaf blade linear, others reduced, bractlike. Rhipidia 1–2-flowered; outer spathe 18–22 mm, inner 25–30 mm, apex dry. Tepals pale blue, lanceolate, ca. 20 mm; filaments connate into tube, 1–2 mm; anthers (4–)6–8 mm; ovary oblong, 6–8 mm; style branching ca. 2 mm above apex of filament tube; branches ca. 2.5 mm. Capsules oblong, truncate, 10–15(–20) mm. Seeds compressed with winged angles, ca. 2.5 × 1.5 mm.
Phenology: Flowering Apr–Jul.
Habitat: Limestone barrens, bluffs, wet prairies
Ark., Mo., Okla.
The flowers of Nemastylis nuttallii open ca. 5 p.m., and close ca. 7 p.m. The name N. coelestina (W. Bartram) Nuttall has long been used for this species, but in fact that name properly applies to a different entity, Ixia coelestina W. Bartram.