18. Poikilospermum Zippelius ex Miquel, Ann. Mus. Bot. Lugduno-Batavi. 1: 203. 1864.
锥头麻属 zhui tou ma shu
Chen Jiarui (陈家瑞 Chen Chia-jui); Ib Friis, C. Melanie Wilmot-Dear
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.
About 27 species: from Sino-Himalayan region through Malaysia to the Bismarck Archipelago; three species in China.
The systematic position of Poikilospermum is controversial. Morphologically, this genus is rather intermediate between the Moraceae and Urticaceae. Berg (1978) separated it and five other genera from Moraceae to establish a new family, Cecropiaceae. However, Poikilospermum has been here treated as a member of Urticaceae on the basis that the ovules of all species of the genus are orthotropous and basally fixed, a characteristic of the Urticaceae.