Shrubs or tall, woody climbers, without stinging hairs. Leaves alternate, petiolate; stipules often caducous, intrapetiolar, connate, leathery; leaf blade often large, leathery, often prominently pinnately veined, margin entire; cystoliths in circular groups adaxially, along veins abaxially, either punctiform or linear. Inflorescences of solitary, axillary, dichotomously branched cymes, unisexual (plants dioecious); glomerules capitate, on swollen peduncular receptacles (in P. subgen. Ligulistigma, continental Asia group), in agglomerations, or free (in P. subgen. Poikilospermum, E Malaysia group). Male flowers: perianth lobes 2-4, free or slightly connate; stamens 2-4, filaments straight (in P. subgen. Ligulistigma) or inflexed; rudimentary ovary present. Female flowers: perianth lobes 4, clavate-tubular, decussate-imbricate. Ovary enclosed; style short; stigma capitate or ligulate (in P. subgen. Ligulistigma); ovule orthotropous. Achene oblong, ellipsoid, or ovoid, slightly compressed, either enclosed by persistent perianth (in P. subgen. Ligulistigma) or exserted from it; pericarp easily separating into 2 valves. Seeds with little or no endosperm; cotyledons ovate.