Dyer’s greenwood (Genista tinctoria)
Dyers greenwood, also known as dyer’s broom (not to be confused with the weedy broom, Cytisus scoparius) contains luteolin, which gives a clear, yellow dye that withstands washing and light. The growing tops are used to produce the best dyes. Harvest the flowering tips about two weeks after they bloom. This plant has excellent cold hardiness and can grow in any light, well-drained soil.