This section is from the book "Handbook Of Hardy Trees, Shrubs, And Herbaceous Plants", by W. Botting Hemsley. Also available from Amazon: Handbook of hardy trees, shrubs, and herbaceous plants.
Calyx obtuse or scarcely turbinate at the base. Petals almost equal, the carinal connate at the back. Pod stalked, ovoid or globose, inflated, often coriaceous. Leaves digitately trifoliolate, or simple and sessile, or perfoliate. A North American genus of about fourteen species of no particular interest, and rarely seen in cultivation. Name from to dye, some species being used for this purpose.
1. B. tinctoria. - A dwarf perennial with slender stems about 18 inches high and scattered trifoliolate leaves; leaflets sub-orbicular. Flowers yellow, in terminal loose racemes, appearing in Summer.
2. B. alba. - A taller plant, more densely clothed with foliage; leaflets oval. Flowers white.
3. B. australis. - Similar to the last, with lanceolate leaflets and blue flowers. Both this and the last flower in early Summer.