Barney Lipscomb from Flora of North America (vol. 2)
Trees conic, evergreen. Bark initially smooth, with resin blisters; in age reddish brown, corky, furrowed. Branches often pendulous, irregularly whorled; short (spur) shoots absent; leaf scars transversely elliptic, slightly raised proximally but essentially flush with twig distally. Buds elongate, not resinous, apex acute. Leaves borne singly, persisting 6--8 years, alternate, short-stalked, flattened; resin canals 2, marginal. Cones borne on year-old twigs. Pollen cones axillary. Seed cones maturing first season, shed whole, deflexed or pendent, ellipsoid, ovoid, or cylindric, nearly sessile, lacking apophysis and umbo; scales persistent, apex rounded; bracts ± exserted, apex 3-lobed, lobes with acute apices, central lobe narrow, longer than lateral lobes. Seeds winged; cotyledons 6--12. x =12, 13.
Species within checklist: