Sanicula sandwicensis is an erect perennial herb in the Apiaceae (parsley) family, 20 to 70 cm (0.7 to 2.3 ft) tall, with a caudex (structure between stem and root) arising from a vertical fusiform (tapering at both ends) root. Solitary stems are profusely branched. Numerous basal leaves are chartaceous (papery), orbicular, 3 to 12 cm (1.2 to 4.7 in) wide, palmately 3- to 5-parted nearly to the petiole (leaf stem). Yellow flowers are arranged in umbels (terminal clusters) of 2 to 5, and 20-flowered. Perfect flowers number 3 to 7; staminate flowers about 15. Ovoid fruit are 3.5 to 4 mm (0.14 to 0.16 in) long and 3 mm (0.1 in) wide, covered with stout, hooked, strongly bulbous prickles, with a linear scar.