Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Genus Description - Female cones indehiscent, berry-like or drupe-like, usually colored (commonly bluish), the several scales coalescent and somewhat fleshy at maturity; seeds 1–10 per cone, wingless; male cones with numerous microsporophylls; dioecious or occasionally monoecious shrubs or small trees with scale-like or needle-like lvs opposite or whorled in 3’s; 2n=22. 60, mainly N. Temp.