Description from Flora of China
Fleurya Gaudichaud-Beaupré; Sceptrocnide Maximowicz; Urticastrum Heister ex Fabricius, nom. rej.
Herbs or subshrubs, armed with stinging hairs. Leaves alternate, petiolate; stipules deciduous, intrapetiolar, incompletely connate, apex 2-cleft; leaf blade papery, pinnately veined or 3-veined, margin often coarsely dentate or serrate, rarely entire; cystoliths punctiform or botuliform. Inflorescences solitary, axillary, pedunculate, loose glomerules forming panicles or sometimes racemes or spikes, unisexual (plants monoecious or dioecious); bracts present, very small. Male flowers: perianth lobes 4 or 5, slightly subvalvate, depressed, inflexed in bud; stamens 4 or 5; rudimentary ovary clavate or subglobose. Female flowers: perianth lobes 4, free or connate at base, strongly unequal, dorsal-ventral 2 greatly unequal and smaller, lateral 2 equal and larger; staminodes absent. Ovary at first straight, soon oblique, ovoid; style usually filiform; stigma often linear, at length often reflexed, papillose on 1 side; ovule orthotropous. Achene ovoid to semicircular, often compressed, sessile or stipitate on oblique torus, usually reflexed on dorsiventrally or laterally winged pedicels. Seeds with thin or no endosperm; cotyledons broad.
The stem fibers are used to make ropes. The stinging hairs are poisonous.
About 28 species: pantropical; seven species (two endemic) in China.
(Authors: Chen Jiarui (陈家瑞 Chen Chia-jui); Ib Friis, C. Melanie Wilmot-Dear)