Plant: Aquatic perennial forb Leaves: linear leaves in whorls about the stem Fruit: Fruits on small peduncles in leaf whorls; with horn-like appendages on margins Notes: Stems filiform and jointed. Plants aquatic. Perianth cuplike. Male and female flowers enclosed by a hyaline, spathlike sheath in the bud. Leaves 1-nerved. References: Kearney & Peebles; Arizona Flora. McDougall; Seed plants of Northern Arizona. Hickman, ed.; The Jepson Manual. ASU specimans