Genista tinctoria L. - Fabaceae - dyer's greenweed, Färber-Ginster

European deciduous shrub, up to 60-90cm tall, native from Europe to Siberia, naturalized in Northern America; stems woody, slightly hairy, branched; leaves alternate, nearly sessile, glabrous and lanceolate; flowers golden yellow, borne in erect narrow racemes from spring to early summer.
http://en.wikipedia.org/wiki/Genista_tinctoria

The dried branches with leaves and flowers are used as diuretic to support the treatment of diseases of the urinary tract. They contain chinolizidin alkaloids like cytisine, methylcytisine and anagyrin; flavanoids, especially dervitives of luteolin, isoflavones such as genistein; traces of tannins and essential oil.
[Herbal Drugs and Phytopharmaceuticals, Max Wichtl, 1989]

„The Romans used dyer's greenweed for dyeing linen and wool. Twigs, leaves and flowers …contain the yellow dyes genistein and luteolin. Harvest usually takes place before flowering. The color is non-fading. Dyeing is carried out on prepared wool. By staining with alum, the wool is lemon yellow, by treatment with iron (II) sulfate dark brown, olive green with copper sulfate.“
http://de.wikipedia.org/wiki/F%C3%A4rber-Ginster

Lindman, C.A.M., Bilder ur Nordens Flora, vol.2, t.332 (1922-1926)
http://plantgenera.org/species.php?id_species=457853

Genista tinctoria in cultivation, CC BY-SA 3.0, Author: Andreas Kraska