From The Collaborative International Dictionary of English v.0.48:
Vert \Vert\, n. [F., green, from L. viridis. See Verdant, and
cf. Verd.]
1. (Eng. Forest Law)
(a) Everything that grows, and bears a green leaf, within
the forest; as, to preserve vert and venison is the
duty of the verderer.
(b) The right or privilege of cutting growing wood.
[1913 Webster]
2. (Her.) The color green, represented in a drawing or
engraving by parallel lines sloping downward toward the
right.
[1913 Webster]