Herbs, rarely somewhat woody, with watery acrid juice, alternate leaves and racemose or corymbose white, yellow, or pink flowers; sepals and petals 4; stamens 6, rarely fewer; pistil 1, consisting of 2 united carpels.

Caudex much branched, branches short and slender. Leaves strongly keeled, ¼—¾ of an inch long, more or less loosely stellate-pubescent, sometimes ciliate at the base. Scapes slender, ¼—6 inches high, hairy or nearly smooth; racemes few-flowered; sepals with a few long hairs or smooth petals ⅛ of an inch long, pale yellow, darker at the base; pod ¼ of an inch or more long, narrowly oblong, acute at both ends, on pedicels ¼ of an inch or more long; style distinct.

In dry, exposed stony places throughout the Rockies, flowering in early spring.

Stems much branched from the root, densely tufted at the base. Leaves erect, linear, obtuse, tapering to the base, stiff, ciliate, with stellate hairs on both sides, especially toward the apex. Scapes naked; flowers racemose; calyx smooth or with scattered hairs, petals white or pale yellow, obovate, ⅛ of an inch or more long, pods short, nearly orbicular, acute at the apex, more or less rounded at the base, sparingly short-hairy, ⅛ of an inch long; style ⅓ its length. Alpine summits and dry ridges throughout the Rockies; flowering in May and June.

Densely cæspitose. Leaves linear-oblong, obtuse, ⅛ of an inch long or less, stiff and rigid, densely imbricated, forming numerous small rosettes: stellate-pubescent on both sides. Scapes slender, 1—2 inches high, few-flowered, petals pale yellow or white, ⅛ of an inch long; twice as long as the hairy calyx; pods ⅛ of an inch or less long with short stiff hairs.

On exposed rocks and alpine summits throughout the Rockies, frequent in the vicinity of Banff, flowering in May and June.

Caudex with numerous slender matted branches. Leaves in dense tufts, oblanceolate, acutish with a rather stout mid-nerve, entire, white-hairy, with dense stellate pubescence, not at all ciliate or slightly so near the base, ¼ of an inch long or less. Scapes slender, hairy, 1—3 inches high, calyx hairy; flowers ⅛ of an inch high, the white petals slightly exceeding the calyx; pods few, usually smooth, oblong, acute at each end, ½ of an inch or less long on short pedicels and with a short stout style and 2-lobed stigma.

On alpine summits and exposed ledges throughout the Rockies; flowering in June.

Similar to the preceding species but with the leaves obtuse; pods ⅓—⅔ of an inch long, smooth, very narrow and usually more or less twisted, on slender pedicels ¼—½ an inch long.

In moist or shaded ground, on alpine summits or on ledges, throughout the Rockies; flowering in June.

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.

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.

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.

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.

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.

In wet shaded places, sparingly throughout the region; flowering during June and July.

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.

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.

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.

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.

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.

Very variable in foliage, finely stellate-pubescent and usually cinereous-villous with larger single hairs; caudex stout, branched. Leaves soft in texture, usually deeply pinnatifid with 2-several pairs of linear to obovate, obtuse segments. Stems several, 1—6 inches high, racemes at first dense and corymbose, becoming elongated in fruit. Flowers white with exserted broad rounded petals ⅛ of an inch or more long; pods usually lanceolate, tapering to each end.

On alpine summits through the Rockies; not common; flowering in June and July.

Erect, 2—4 feet high, freely branching, smooth or nearly so. Lower leaves runcinate-pinnatifid, petioled, the lobes lanceolate, often auriculate; upper leaves smaller, short petioled, or usually sessile, very deeply pinnatifid, the lobes linear or lanceolate, dentate or entire, the uppermost often reduced to linear, entire bracts. Flowers pale yellow, ¼ of an inch broad on slender spreading pedicels, pods very narrowly linear, divergent, 2—4 inches long.

At the lower elevations throughout the region as a weed, especially on the line of the railway, flowering in July.

Stems 1—2 feet high, sparingly greyish-puberulent, especially below, or sometimes nearly smooth, often glandular above; hairs more or less stellate. Leaves twice or thrice-pinnatifid, the primary divisions oblanceolate or obovate, divided to near the midrib into linear or linear-oblong segments, sparingly puberulent. Raceme rather long, flowers small, less than ⅛ of an inch high; petals yellow; peduncles diverging sometimes nearly at right angles; pod club-shaped.

Common throughout the Rockies in open places at the lower altitudes, flowering in June and July.

Erect 4—10 inches high, branching below, sparingly hairy. Leaves spatulate or oblanceolate, the lower obtuse, 1—2 inches long, narrowed into a petiole, sharply dentate or rarely entire, the upper smaller, narrower, often acute. Flowers white or pink ⅛ of an inch or more broad, pedicels erect, ¼ of an inch long in fruit; pods nearly terete, narrowly linear, ½—¾ of an inch long, valves finely nerved.

In moist gravelly or stony ground throughout the Rockies at the lower altitudes, flowering in June.

Aquatic, smooth, branched, floating or creeping, rooting from the joints. Leaves odd-pinnate of 3—9 segments, the terminal one larger than the lateral, all obtuse, ovate or oval or the terminal one nearly orbicular. Racemes elongated in fruit; flowers white, ⅛ of an inch or more broad; pod ½—1¼ inches long, spreading and slightly curved upwards, on pedicels of about their length.

In ditches and shallow pools through the Rockies, especially abundant at Banff in the warm water at the outlet from the Basin; flowering through June and July.