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..
Monoecious, scape slender, erect, 1°-21° high, simple, bearing 4 or 5 verticils of flowers at or above the surface of the water. Leaves long-petioled, spongy and rigid, reduced to slender phyllodia or bearing linear-lanceolate or elliptic blades 2'-4' long and 3"-I2" wide; bracts acute, 2"-4" long, much shorter than the slender fertile pedicels; flowers 8"-10" broad; stamens about 24; filaments dilated, pubescent, at least at the middle, longer than the anthers; achene obliquely obovate, the dorsal margin with a broad crenate wing, the ventral straight-winged, each side bearing 2 crenate crests, the beak short, oblique.
In shallow water, Iowa and Minnesota. Phyllodia are commonly developed from the nodes of the rootstock. July-Aug.
Monoecious, scape very slender, 4'-6' tall, Leaves represented by flat phyllodia which are attenuate from broad bases and often also by longer blade-tipped petioles, the blades linear or narrowly linear-lanceolate, 10"-17 1/2" long, acute or acuminate; bracts ovate, about 1" long, united at the base; pedicels of the pistillate flowers filiform, mostly less than 5" long, those of the staminate flowers longer than the former; sepals ovate to ovate-lanceolate, becoming 1 1/2"-2" long; corolla 3 1/2"-4 1/2" broad; filaments sub-orbicular, pubescent, much shorter than the anthers; anthers suborbicular, conspicuously larger than the filaments; fruits not seen.
On sandy shores, between low and high tide, Massachusetts, Connecticut and Long Island, New York. July-Sept.
Sagittaria graminea Michx. Fl. Bor. Am. 2: 190. 1803.
Monoecious or dioecious, glabrous, scape simple, erect, 4'-2° tall. Leaves long-petioled, the bladas linear, lanceolate or elliptic, acute at both ends, or rarely with spreading or recurved basal lobes, 2'-6' long, 1/2'-3" wide, 3-5-nerved, the nerves distinct to the base, some of them occasionally reduced to flattened phyllodia; bracts ovate, acute, 1 1/2"-3" long, much shorter than the slender or filiform fruiting pedicels, connate to the middle or beyond; flowers 4"-6" broad; stamens about 18; filaments dilated, pubescent, longer than or equalling the anthers; achene obovate, 1/2"-1" long, slightly wing-crested on the margins and ribbed on the sides, the beak very short.
In mud or shallow water, Newfoundland to Ontario and South Dakota, south to Florida and Texas. Early leaves often purplish. July-Sept.