This section is from the book "British Wild Flowers - In Their Natural Haunts Vol5-6", by A. R. Horwood. Also available from Amazon: A British Wild Flowers In Their Natural Haunts.
Mountain Bitter Cress (Cardaminc impatiens, L.) - The habitat of this plant is woods, shady copses, talus slopes, rocks, hilly districts, preferably on limestone. The habit is as in the last, but the stem smooth, more leafy, and branched.
The rootstock is spindle-shaped. The leaves have lobes each side of a common stalk, the leaflets stalked, lance-shaped, with narrow, sharp divisions, the lower egg-shaped, 3-lobed, the upper oblong, lance-shaped. The leaf-stalks have bent-back, arrow-shaped lobes at the base, fringed with hairs. The flowers are white (1/4 in.), in a panicle, the petals erect, linear, egg-shaped. The anthers are yellow, and the style is slender. The pods are shortly stalked and erect, with many seeds. The plant is 9-24 in. in height, flowering between June and September, and is annual or biennial, and herbaceous.
The habitat of this plant is woods, copses, and shady places. The thick rootstock is white, hence the English name, scaly, and creeping, the knobs tooth-like. Thestem iserect, simple, leafless below. The lower leaves have lobes each side of a common stalk, the leaflets lance-shaped; the upper simple, entire, alternate, with bulbils in the axils (hence the Latin specific name), the margin sometimes toothed, or fringed with hairs. The flowers are large, rose-colour or purple, lilac or white. The flower-stalk is slender. The pods are erect. Seed is rarely matured. The plant is 1-2 ft. high, and flowers in April and May, being a herbaceous perennial.