A genus of three species of trees, one in western North America, the other two (closely related to each other) in eastern Asia. Leaves scale-like, decussate, appressed except at the tip. Branchlets flattened, arranged in sprays. Female cones with six scales, each with a small mucro on the back near the apex, the lowermost pair small, sterile, the next pair fertile, the uppermost pair sterile, narrow, united into a plate. Seeds two to each fertile scale, unequally two-winged. See further in Volume II, pages 564-5 and also under Libocedrus in this supplement.