Pubescent throughout with short stellate hairs; stems rather stout, erect, frequently several from the same root; leafy, 2—15 inches high. Leaves entire or few-toothed, oblanceolate or lanceolate, stem leaves usually narrowed and frequently ciliate at the base, ½—2 inches long. Flowers bright yellow in an elongated leafy raceme; calyx smooth or somewhat hairy; petals elliptic, less than ⅛ of an inch long; pods lanceolate to linear, acute, hairy, often twisted, ¼—½ an inch long on peduncles half their length. Frequent in dry open ground at the lower altitudes throughout the Rockies; flowering in June. [Sidenote: =Draba incana= L. _Hoary Whitlow-grass._] Erect, simple, or somewhat branched, leafy, stellate-pubescent throughout, 6—12 inches high. Leaves lanceolate, oblanceolate or ovate, ¼—1 inch long, acute or obtuse, dentate or nearly entire; flowers white, ⅛ of an inch or less broad; petals notched, twice as long as the sepals; pod oblong or lanceolate, acute ⅓—½ an inch long on nearly erect pedicels about ½ their length. Throughout the region in moist ravines; flowering during June. Other species of Draba occur in the region but being neither common nor striking it is deemed out of place to describe them here. [Illustration: Physaria didymocarpa (Hook.) A. Gray. (⅔ Nat.) Bladder-Pod.] [Illustration: Smelowskia calycina (Desv.) C. A. Meyer. (⅔ Nat.) Smelowskia.] [Sidenote: =Thlaspi arvense= L. _Penny-cress._] Decumbent or erect, 6—12 inches high, simple or much branched above. Leaves spatulate or oblong, obtuse, obtusely- or runcinately-toothed or angled. Flowers small, white, in a compact head; pods large, ½ an inch broad, orbicular or nearly so, strongly winged and compressed. In moist low ground and waste places throughout the Rockies, flowering in June. [Sidenote: =Physaria didymocarpa= (Hook.) A. Gray. _Double Bladder-pod._] Densely stellate, canescent, pale green, root long and deep. Stems decumbent or ascending, slender, simple, 3—12 inches long. Leaves spatulate, the basal ones obtuse, entire or few lobed, narrowed into margined petioles: stem leaves nearly sessile, acute, much smaller. Flowers about ½ an inch broad, light yellow in a close raceme, 2—5 inches long in fruit; pods much inflated and variable, often ½ an inch thick. In dry clayey and stony soil and on slopes throughout the Rockies; flowering in June. [Sidenote: =Cardamine pennsylvanica= Muhl. _Pennsylvania Bitter-cress._] Smooth or rarely with a few scattered hairs; stems erect, stout or slender, 8 inches to 3 feet high, usually much branched, somewhat succulent, leafy up to the racemes. Basal leaves 2—6 inches long, the terminal leaflet obovate, ovate or obcordate, usually narrowed at the base, ¼—¾ of an inch wide, the lateral 4—8 pairs oblong, oval or obovate, all toothed or some of them entire. Flowers about ⅛ of an inch broad, white; pods very narrowly linear, ½—1¼ inches long, erect when mature on ascending pedicels.