Echinodorus tenellus (Mart.) Buchenau
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Species Description - Delicate stoloniferous perennial, simple, erect, to 1 dm; lvs with long-petiolate, linear to more often elliptic or lanceolate blade 1–3 cm, or phyllodial and bladeless when submersed; fls in 1 (or 2) whorls of 3–6, the slender pedicels usually recurved at the tip; bracts minute, 1–3 mm; sep orbicular-ovate, 1–2 mm, appressed in fr; pet white or pink, suborbicular, 1–3 mm; stamens 6 or 9; anthers basifixed, 0.2 mm; achenes 10–20 in a loose head, dark red to nearly black, 1 mm, 8-ribbed, virtually beakless. In mud or wet sand or shallow water; trop. Amer., n. to se. U.S. and irregularly in the Atlantic states (mainly on the coastal plain) to Mass. (where now wanting), and up the Mississippi R. to Ill. and Mo.; irregularly to Kans., sw. Ky., and formerly Mich. Our plants, as here described, are var. parvulus (Engelm.) Fassett. (E. parvulus)