Quassia is a
genus of
evergreen tropical Asian trees and
shrubs (family
Simaroubaceae), counting about 40
species. Best known is
Bitterwood[?] (
Quassia amara), a tree up to 6 meters (20 feet) tall. Its
heartwood[?] contains
quassiin[?], a bitter-tasting substance that was used in
medicine.