dyer's greenweed in American English
noun: an ornamental Eurasian shrub, Genista tinctoria, whose flowers yield a yellow dye formerly used with woad to make a permanent green dye; woadwaxen
dyer's-greenweed in British English
noun: a small Eurasian leguminous shrub, Genista tinctoria, whose yellow flowers yield a yellow dye, formerly mixed with woad to produce the colour Kendal green