It is a perennial herb that grows submerged in water and has roots. The stem is slender and extensively branched, producing rhizomes that spread horizontally. The leaves are arranged in whorls, without stalks, and are oblong or spear-shaped, typically green with reddish-brown markings. The leaf margins are sharply serrated, and the tips are pointed. The flowers are solitary and inconspicuous, and the plant can be either monoecious or dioecious.