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]