Pontederia cordata is a stout perennial herbaceous emergent that can reach four feet tall. The light green stems and leaves emerge annually from a thick pad of fibrous roots. These roots give rise to short creeping rhizomes, allowing the plant to spread. The waxy leaves develop at the ends of stems, and are highly variable in shape and size. Their shape will range from oval to lance-like, with size varying 2 to 10 inches long and 1/2 to 6 inches wide. Leaf veins are orientated in a parallel arrangement starting at the base.
The compound, violet to blue flowers emerge from an erect spike. The spike will grow to 6 inches in length. The showy flowers appear anywhere from May to October over much of its range. The corky fruit produced by these flowers is oblong and one seeded.