The Collaborative International Dictionary of English v.0.48:
Yacca \Yac"ca\ (y[a^]k"k[.a]), n. (Bot.) A West Indian name for two large timber trees (Podocarpus coriaceus, and Podocarpus Purdicanus) of the Yew family. The wood, which is much used, is pale brownish with darker streaks. [1913 Webster]