Raphanus tenellus Pallas, Reise Russ. Reich. 3: 741. 1776; Chorispermum tenellum (Pallas) R. Brown

Plants papillose, sometimes pubescent, papillae sometimes mixed with simple trichomes. Stems (0.5-)1-4(-5.6) dm. Basal leaves (often withered by flowering); petiole (0.5-)1-2(-4) cm; blade oblanceolate or oblong, (1.5-)2.5-8(-13) cm × (4-)8-20(-30) mm, base cuneate or attenuate, apex acute, surfaces glandular. Cauline leaves similar to basal, distalmost subsessile, blades smaller distally. Fruiting pedicels (2-)3-5 mm, glandular. Flowers: sepals purplish, (3-) 4-5(-6) × 0.5-0.7 mm; petals 8-10(-12) × 1-2 mm, claw 6-7 mm; filaments 4-6(-7) mm; anthers ca. 1.5 mm. Fruits slightly curved-ascending, (1.4-)1.8-2.5(-3) cm × 1.5-2 mm, with 8-12 constrictions on each side; style (6-)10-18(-22) mm. Seeds brown, 1-1.4 × 0.8-1 mm. 2n = 14.

Flowering Apr-Jul. Waste places, pastures, fields, roadsides, railroad embankments, grassy slopes; 0-2300 m; introduced; Alta., B.C., Sask.; Ariz., Calif., Colo., Idaho, Ill., Ind., Iowa, Kans., La., Mass., Mich., Mo., Mont., Nebr., Nev., N.Mex., N.Y., N.Dak., Ohio, Okla., Oreg., S.Dak., Tenn., Tex., Utah, Wash., Wyo.; Europe; Asia; n Africa; introduced also in South America.

Chorispora tenella appears to be most widely distributed in Colorado, Nevada, and Wyoming, of all the provinces and states listed above.