This section is from the book "Wayside And Woodland Blossoms", by Edward Step. Also available from Amazon: Wayside And Woodland Blossoms: A Guide To British Wild-Flowers.
The Kidney-vetch or Lady's fingers was celebrated from early times as a plant that was efficacious in the cure of wounds, and hence its specific name vulneraria. There is no doubt that this reputation was well-founded, for its bluish leaves are covered with silky hairs and its calyces downy. It is a perennial herb that affects dry pastures and rocky banks. From a woody rootstock arise several stems and a large number of radical leaves; these consist of a long terminal leaflet and two disproportionately small lateral leaflets. The leaves from the stems (caudal leaves) have a larger number of leaflets in pairs, as well as a terminal one. The flowers are borne in heads, with an involucre of leaflets, and the heads are chiefly in pairs. The calyx is membranous, and therefore permanent, the mouth oblique, with fine teeth. The petals are nearly equal in length, and typically yellow, but subject to considerable variation. After flowering the straw-coloured calyx becomes inflated, and the roundish smooth and veined pod with its solitary seed is hidden within. In some of the coast localities for this plant it will be found with flowers white, cream-coloured, crimson, and purple; this has been especially noted at the Lizard in Cornwall. It is ordinarily in flower from June to August. This is the only British species.
The name is the one in use among the ancient Greeks, and signifies bearded flower, which is obviously a reference to the woolly calyces.