Herb forming dense masses up to 2 m. diam. and tall. Stems much-branched, arising from thick, fleshy rhizome, up to c. 4 cm. diam. Lvs on semiterete, sparingly hairy petioles up to c. 6 dm. long; sheath amplexicaul, produced above into a foliaceous lobed ligule. Lamina bright green above, paler below; veins prominent on both surfaces, flabellate; 20-35 (from sinus) × 30-45 cm., suborbicular-reniform, somewhat fleshy, clad on both surfaces with slender ± appressed hairs ± 1-2 cm. long or nearly glab. below; margins with ∞ irregular, broadly rounded-triangular, abruptly apiculate or toothed lobules. Umbels compound, axillary and terminal, up to c. 30 cm. diam. on very stout peduncles 10-15 cm. long, bearing patent slender hairs. Primary rays ± 5-10, up to c. 15 cm. long, stout; bracts foliaceous, us. deeply 3-(5)-lobed. Secondary rays ± 10, up to c. 5 cm. long; bracts smaller. Pedicels rather slender, ± 10 mm. long, bracts often entire. Fls ∞, ± 5 mm. diam.; petals waxy, yellow, with purple base. Fr. subglobose, shining, hollowed above, ± (4)-5-(6) mm. diam.

2n = 48