Annuals, 15-40(-60) cm.
Stems branched; hairs stalked, glandular throughout.
Leaves: petiole green to purple, angled, (0.2-)0.5-0.8(-1) cm; leaflet blade linear to narrowly elliptic, 1.5-2.8 × 0.1-0.2 cm, margins entire, apex acute, mucronulate, surfaces densely glandular abaxially, sparsely glandular adaxially.
Racemes 1-3 cm (6-8 cm in fruit); bracts trifoliate, ovate, 5-15 mm.
Pedicels 5-15 mm.
Flowers: sepals pale yellow, glandular, lanceolate, 1.6-2.6 × 0.8-1.2 mm, margins entire, apex acute to obtuse; petals white, oblong-ovate, clawed, abaxial pair 1.5-3 × 1-2 mm (6 or 7-lobed), apex emarginate to lacerate, adaxial pair 3-5 × 2-3 mm (4 or 5-lobed), apex emarginate to lacerate; nectary glands yellow (drying purple), 0.5-1 mm; stamens 6-9, slightly exserted, yellow, 3.2-5.2 mm; anthers yellow, 0.5-1 mm; gynophore 2-4 mm in fruit; ovary 2.5-5(-7) mm; style persistent in fruit, 2.5-4.5 mm; stigma red.
Capsules 8-30 × 2-4 mm, reticulate, glandular.
Seeds 18-36, bright reddish brown, globose to oblong, 1.8-2 mm, pebbled (without transverse ridges).
2n = 20. Flowering summer-early fall. Sandy soil, often in blowouts in prairies and stabilized dunes; of conservation concern; 200-1400 m; Colo., Ill., Ind., Iowa, Minn., Nebr., N.Mex., Ohio, Okla., S.Dak., Tex., Wis. Populations of
Polanisia jamesii in Indiana and Ohio are adventive.
