Alyssum incanum Linnaeus, Sp. Pl. 2: 650. 1753

Plants densely pubescent, trichomes appressed, stellate mixed with simple ones. Stems simple or few from base, (2-)3-8(-11) dm. Basal leaves (withered by flowering) : blade oblanceolate, (2.5-)3.5-8(-10) cm, base cuneate or attenuate, apex obtuse. Cauline leaves: blade apex acute or obtuse. Fruiting pedicels appressed to rachis, (4-)5-9(-12) mm. Flowers: sepals 2-2.5 mm; petals narrowly obcordate, (4-)5-6.5(-8) mm (lobes oblong, (1-)1.5-3 × 0.5-1.5 mm); filaments white, median pair 2-3.3 mm, lateral pair 0.3-1 mm; anthers 0.5-1 mm. Fruits (4-)5-8.5(-10) × (2-)2.5-4 mm; valves obtuse at both ends, trichomes sometimes with unequal rays; style 1-4 mm, sparsely pubescent basally. Seeds slightly flattened, narrowly margined, 1-2.3 mm diam. 2n = 16.

Flowering May-Sep. Flood plains, meadows, waste places, railroad embankments, woodlands, grasslands, roadsides, fields, stream banks, pastures, hillsides, forest floor; 0-2800 m; introduced; B.C., Man., N.B., Ont., Que., Sask.; Ariz., Calif., Colo., Conn., D.C., Idaho, Ill., Ind., Iowa, Kans., Maine, Mass., Mich., Minn., Mo., Mont., Nebr., Nev., N.H., N.J., N.Y., N.Dak., Ohio, Oreg., Pa., R.I., S.Dak., Utah, Vt., Va., Wash., W.Va., Wis., Wyo.; Europe; Asia.