Alpine Rock Cress (Arabis Alpina, L.)

This plant has the rosette habit. The rootstock is stoloniferous. The barren shoots are prostrate. The stem is smooth or hairy. The hairs on the leaves are 3-4-forked. The radical leaves are oblong, blunt, stalkless, or narrowed into the leaf-stalk, which is short and winged. The stem-leaves are lance-shaped, oblong, auricled, spreading, with irregular teeth, and some secondary teeth. The outer sepals are gibbous below. The flowers are white, the petals large, twice as long as the sepals. The pods are spreading or curved upwards, broad, blunt. The seeds are round to oval, with a narrow membranous wing. The plant is 4-9 in. high, flowering in July and August, and is a herbaceous perennial.

Rock Cress (Arabis Petrcea, Lam.)

The habitat of this plant is alps, moist rocks. The plant has the rosette habit. The stem is erect or prostrate, smooth, hair)-, branched below. The leaves are stalked, the radical leaves lyrate, or deeply divided nearly to the base, long-stalked, oblong to ovate, the stem-leaves nearly entire. The segments are short. The leaves are smooth, or have forked hairs. The flowers are large, white or purplish, in a corymb. The petals have a broad claw, and are spreading. The pods are spreading, with 3-nerved valves, slender, straight. The seeds are oblong, with a terminal, straight, indistinct wing. The plant is 3-8 in. high, flowering in July and August, and is a herbaceous perennial.

Bristol Rock Cress (Arabis Stricta, Huds. = A. Scabra, Ah.)

The habitat of this plant is calcareous rocks, limestone cliffs. The plant has the rosette habit. The plant bears stiff hairs below. The stems are erect or ascending. The radical leaves are more or less narrowed into a stalk, small, blunt, deep-green, fringed with forked and simple hairs, lobed or toothed, the lobes oblong or triangular. The stem-leaves are few, stalkless, half-clasping. The flowers are white or cream-colour, rather large. The petals are narrow, wedge-shaped, nearly erect. The style is short. The pods are few, distant, nearly erect, or spreading, straight, three to six times as long as the stalks. The valves are i-nerved. The seeds are oblong, winged at the tip. The plant is 4-9 in. high, flowering in April and May, and is a herbaceous perennial.

Fringed Rock Cress (Arabis Ciliata, Br.)

The habitat of this plant is walls, banks, rocky seashores in Ireland. It is a local species. The plant has the rosette habit. The plant is smooth or fringed with hairs. The stem is erect. The leaves are inversely ovate, smooth or hairy, or fringed with hairs, toothed, nearly stalkless. The stem-leaves are stalkless, rounded below, elliptic. The flowers are white. The pods are few, broad, erect, straight. The seeds are not winged, and are close. The plant is 4-6 in. high, flowering in July and August, and is a herbaceous biennial.

Tower Mustard (Arabis Glabra, Bernh. = Tur-Ritis Glabra, L. = A. Perfoliata, Lam.)

The habitat of this plant is dry banks, cliffs, dry rocky places S. of Perth, and Ireland (Antrim). The habit is erect. The stem is straight. The plant is nearly smooth, or with few spreading hairs, bluish-green. The radical leaves are stalked, inversely ovate, lobed, hairy, soon withering. The stem-leaves are clasping, entire, auricled, smooth. The flowers are pale-yellow, the petals erect. The style is short. The pods are numerous, crowded, slender, erect, on slender stalks. The seeds are in 2 rows, very small, oblong, angled. The plant is 1-3 ft. high, flowering in May to July, and is a herbaceous biennial.