Mostly dioecious, much branched, erect or climbing shrubs. Branches usually green. Leaves opposite or whorled, often reduced to membranous sheaths. Reproductive organs axillary, opposite or arranged in whorls of 3 or 4 cones, each cone composed of 2-8 decussate pairs of bracts, the lower pair (or pairs) sterile, the others fertile. Staminate flowers of 2 opposite scales (perianth) subtending the single column of stamens; anthers 2-8, at end of column, sessile or stalked, each with 2-3 pollen sacs dehiscing by a terminal pore. Ovulate flowers in groups of 1-3, each consisting of 2-4 connate bracts (perianth) and an ovule with 2 pairs of bracts forming the outer and inner integuments, the latter terminating in an elongated style-like micropyle (micropylar tubule). Seed enclosed in the leathery, winged or fleshy integuments; cotyledons 2.