This section is from the book "An Illustrated Flora Of The Northern United States, Canada And The British Possessions Vol1", by Nathaniel Lord Britton, Addison Brown. Also available from Amazon: An Illustrated Flora of the Northern United States, Canada and the British Possessions. 3 Volume Set..
Sp. PI. 1015. 1753.
Aquatic dioecious submerged perennials, with long grass-like floating leaves. Staminate flowers with a 2-3-parted spathe on a short scape, numerous, nearly sessile on a conic receptacle; perianth 3-parted; stamens generally 2 (1-3). Pistillate flowers on a very long flexuous or spiral scape, with a tubular, 2-cleft, 1-flowered spathe; perianth-tube adnate to the ovary, 3-lobed and with 3 small petals; ovary 1-celled with 3 parietal placentae; stigmas 3, nearly sessile, short, broad, 2-toothed with a minute process just below each sinus; ovules numerous, borne all over the ovary-wall, orthotropous. Fruit elongated, cylindric, crowned with the perianth. [Named for Antonio Vallisneri, 1661-1730, Italian naturalist.]
Vallisneria spiralis L. Sp. PI. 1015. 1753.
Plant rooting in the mud or sand, stolon-iferous. Leaves thin, narrowly linear, 5-nerved, obtuse, sometimes serrate near the apex, 1/2°-6° long, 2"-9" wide, the 2 marginal nerves faint; the staminate bud separates from the scape at the time of flowering and expands upon the surface of the water; pistillate flower upon a long thread-like scape, the spathe 1/2'-1' long, enclosing a single white flower; ovary as long as the spathe, after receiving the pollen from the staminate flowers the scape of the pistillate contracts spirally; ripe fruit 2'-7' long.
In quiet waters, New Brunswick and Nova Scotia to North Carolina, west to South Dakota and Indiana. The " Wild or Water Celery " of Chesapeake Bay, and a favorite food of the canvas-back duck. Aug.-Sept.