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.
The habitat of this plant is waste places, chiefly near the sea, and it is scarcely wild except along the coast. The habit is erect or prostrate. The plant is smooth or slightly downy. The radical leaves, which soon wither, are much divided, bipin-natifid, with narrow lobes. The upper stem-leaves are linear, entire. The flowers are in terminal and lateral corymbs, small, white, sometimes apet-alous. There are 2 stamens. The style is short. The pods are oval, narrowed at the end, flat, with a wing, the valves keeled. The seeds are flattened. The plant is 6-12 in. high, flowering from May to July, and is a herbaceous annual.
The habitat of this plant is calcareous places, on limestone. The habit is erect. The stems are branched above, forming a panicle. The branches are ascending, wavy. The stem-leaves are deeply heart-shaped, oblong, with auricles which meet together, and smooth, bluish-green. The radical leaves are spoon-shaped, stalked. The flowers are white, in a raceme or corymb, longer in fruit. The style is very short, included within the notch. The pods are small, inversely heart-shaped, horizontal, like the stalks, the valves broadly winged above, turgid, the marginal nerve short. The seeds are 4-6 in a cell, pale, smooth. The plant is 3-8 in. high, flowering in April and May, and is a herbaceous annual.
The habitat of this plant is mountain pastures, stony places. The habit is erect. The radical leaves are long-stalked, inversely ovate, entire. The stem-leaves are arrow-shaped, narrow, heart-shaped, smooth, and bluish-green. The flowers are white, with a rose tinge, small, in racemes. The style equals the notch. The pods are oblong to inversely ovate, narrowed below, and are curved upwards on spreading stalks, the valves winged above. The marginal nerve is indistinct. The seeds are reddish-brown, smooth, 4-8 in a cell. The plant is 4-15 in. high, flowering from May to October, and is a herbaceous biennial or perennial.
The habitat of this plant is limestone rocks. It differs from the last in having nearly entire leaves. The stem-leaves are oblong, heart-shaped. The flowers are small and white. The style is longer than the notch. The raceme is oval or oblong in fruit. The petals are three times as long as the calyx. The pods are blunt, notched at the tip, with a point (the style), inversely ovate, the notch broad and shallow. The seeds are 4-5 in each cell. The plant is 6-10 in. high, flowering from May to August, and is a herbaceous perennial.
The habitat of this plant is limestone rocks and sand dunes, and about walls. It was planted by Dillenius on the wall of Eltham Churchyard in Kent, and in Mathew Cemetery, York. The habit is prostrate. The stems are smooth or hairy, slender, leafy, branched. The radical leaves have spreading lobes, and are inversely ovate, nearly stalked. The leaves are deeply divided to the base, the segments entire, much-branched from the base. The flowers are in racemes, small, white. The petals are as large as the sepals. The style is distinct. The pods are on horizontal stalks, the raceme loose, long in fruit, the pods blunt both ends. The seeds are pale. The plant is 2-4 in. high, flowering from March to May, and is a herbaceous annual.