Dyers' Greenweed, Dyers' Broom, Genista, a yellow dye plant that grows abundantly around Europe and the Mediterranean. From fresh yellows to goldens, and greens using ferrous sulfate.
 
Genista has a good lightfastness and was a traditional 18th-century dye in the South of France.
 
Dye at around 30% wof.
Heat to moderate heat without boiling. Boiling will dull most yellow dyes.
Adding 1% of calcium carbonate to the dye bath will give clearer yellows.