In wet shaded places, sparingly throughout the region; flowering during June and July. [Sidenote: =Arabis hirsuta= (L.) Scop. _Hairy Rock-cress._] Stem erect, nearly simple, 1—2 feet high, roughly hairy or nearly smooth. Basal leaves on margined petioles forming a rosette, obovate or spatulate, obtuse, denticulate, 1—2 inches long; stem leaves sessile, clasping by an auriculate base, lanceolate or oblong. Flowers ¼ of an inch or less long, white, in a strict, elongated raceme; pods narrowly linear, erect or appressed, 1—2 inches long. In open grounds throughout the Rockies at the lower altitudes; flowering in June. [Sidenote: =Arabis Holboldii= Hornem. _Stony Rock-cress._] Finely stellately pubescent throughout; stems frequently several, simple or branched, erect ½—2½ feet high. Root leaves narrowly oblanceolate, entire, an inch or less long; stem leaves linear-lanceolate to narrowly oblong, acute, sagittate. Flowers rosy pink or rarely white, becoming more or less reflexed, ¼ of an inch long; pods more or less abruptly reflexed, straight or somewhat curved 1½—2½ inches long, very narrowly linear. On banks and stony slopes throughout the Rockies; flowering in June. [Sidenote: =Arabis Drummondii= A. Gray. _Drummond’s Rock-cress._] Slightly glaucous, stems erect; 1—2 feet high. Root leaves narrowly oblanceolate more or less hairy; the stem leaves oblong or linear-lanceolate, 1—2 inches long. Flowers white or pinkish, ¼ of an inch long in a close panicle, elongated in fruit; pods erect when mature, slender, 1½—3 inches long, obtuse. In open ground and on slopes throughout the Rockies, flowering in June. [Sidenote: =Arabis Lyallii= S. Wats. _Lyall’s Rock-cress._] Low, smooth, throughout, or sometimes more or less stellate-pubescent below; stem simple, several, or many from the same root. Lower leaves spatulate or linear-oblanceolate, usually ½—1 inch long, sometimes longer; stem leaves narrowly lanceolate or oblong, sometimes scarcely auricled. Flowers rose-colour, ¼ of an inch long; pods erect or ascending, very slender, straight or nearly so, 1—2 inches long. Alpine meadows and slopes at the higher elevations throughout the Rockies, flowering in June and July. [Sidenote: =Erysimum inconspicuum= (S. Wats.) MacM. _Treacle Mustard._] Erect, 10—18 inches high, cinereous and rough with 2-parted hairs. Leaves narrowly linear-lanceolate or oblong-linear, mostly entire, the root leaves crowded and sometimes repand dentate. Flowers sulphur yellow in a compact head, elongated in fruit, calyx campanulate, ¼ inch high, petals ⅓ longer, the blades spreading; pods slender, erect or nearly so at maturity, 1—2 inches long. In gravelly places, common on the eastern slopes of the Rockies at the lower elevations, flowering in June. [Sidenote: =Smelowskia calycina= (Desv.) C. A. Meyer. _Smelowskia._]