Yes, quassia is a Scrabble word!

Noun

1. A bitter compound used as an insecticide and tonic and vermifuge; extracted from the wood and bark of trees of the genera Quassia and Picrasma

2. Handsome South American shrub or small tree having bright scarlet flowers and yielding a valuable fine-grained yellowish wood; yields the bitter drug quassia from its wood and bark