Low tree, shrub, or erect herb, 1-4 m. high, the branches densely covered with stout bristles or spines; leaves 15-35 cm. long and wide, deeply incised-lobed (lobes acuminate, entire or few-toothed), spiny on the nerves beneath, membranous, glabrescent; inflorescence paniculate, up to 20 cm. long; staminate flowers in glomerules, the pistillate in glomerules or often distinct, sessile; achenes about 1.5 mm. long, suboblique.