The Collaborative International Dictionary of English v.0.48:

Woad-waxen \Woad"-wax`en\, n. [Cf. Wood-wax.] (Bot.)
   A leguminous plant (Genista tinctoria) of Europe and
   Russian Asia, and adventitious in America; -- called also
   greenwood, greenweed, dyer's greenweed, and whin,
   wood-wash, wood-wax, and wood-waxen.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

dyer's broom \dyer's broom\, dyer's-broom \dyer's-broom\n.
   small Eurasian shrub (Genista tinctoria) having clusters of
   yellow flowers that yield a dye; common as weed in England
   and U.S.; sometimes grown as an ornamental.

   Syn: woodwaxen, dyer's greenweed, dyer's weed, dyer's rocket,
        dyeweed, greenweed, whin, woadwaxen, Genista
        tinctoria.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

Genista tinctoria
    n 1: small Eurasian shrub having clusters of yellow flowers that
         yield a dye; common as a weed in Britain and the United
         States; sometimes grown as an ornamental [syn: woodwaxen,
         dyer's greenweed, dyer's-broom, dyeweed, greenweed,
         whin, woadwaxen, Genista tinctoria]