A large upright plant forming large clumps and growing up to 3 m or more in height. It usually grows in water and most of its leaves are tufted at the base of the plant. These leaves have a long and thick stalk and a very large leaf blade (up to 75 cm long and 25 cm wide). Its purple flowers are borne in large branched clusters at the top of the flowering stems. These flowers are partially enclosed in green or purple-tinged hairy bracts (13-28 mm long). Its small fruit (9-12 mm long) are shed from the plant along with the floral bracts.