Monoecious trees, rarely shrubs, mostly resinous. Leaves mostly persistent, solitary or fasciculate, generally spirally arranged, linear, semiterete, terete or compressed-triquetrous, entire or minutely serrulate. Reproductive organs in cones with spirally arranged scales. Staminate cones surrounded at base by a whorl of sterile bracts and consisting of scale-like stamens each with 2 pollen sacs (microsporangia) on the under-surface. Scales of ovulate cones mostly double: the lower one (bract) sterile, the upper (ovuliferous scale) with 2 ovules on its inner surface; mature cones usually woody, closed. Seeds usually winged and 2 on each scale.