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, glabrous, scape erect or ascending, simple or sparingly branched, 1°-2° high. Leaves lanceolate, entire, long-petioled, acute or acuminate at both ends, seemingly pinnately veined, really 5-7-nerved, 5'-8' long, equalling or shorter than the scape; bracts lanceolate, acuminate, s"-8" long, much shorter than the slender fruiting pedicels, connate at the base, papillose; stamens 20-25; filaments glabrous, longer than the anthers; achene about 1" long, oblong, curved, narrowly winged on both margins, its sides smooth and even, its beak short, oblique.
In ponds, Kansas and Oklahoma.
Sagittaria falcata Pursh, Fl. Am. Sept. 297. 1814.
Sagittaria lancifolia falcata J. G. Smith, Mem. Torrey Club 5: 25. 1894.
Monoecious, glabrous to the inflorescence, scape erect, longer than the leaves, sometimes branched. Leaves erect or nearly so, almost linear to elliptic, the blades mostly 4'-16' long, often slightly acuminate, much shorter than the petioles; whorls of the inflorescence few or many; flowers 9'-15" broad; bracts ovate, less than 5" long, obtuse or acutish, granular-papillose; filaments not dilated, pubescent; anthers shorter than the filaments; achene cuneate, about 1" long, narrowly winged, the slender beak usually ascending.
In shallow water and swamps, Delaware to Florida. Texas and Mexico. Sagittaria lancifolia L., admitted as including this species in the first edition, is distinct from it, and inhabits Florida and tropical America.
Monoecious, glabrous, scape simple, weak, curving, ascending or decumbent, shorter than the leaves. Leaves very variable, linear, lanceolate, elliptic or broadly ovate, acute or obtuse at the apex, entire or with 1 or 2 short or slender basal lobes; bracts ovate, obtuse, 2"-4" long, united at the base or sometimes distinct; heads of fruit sessile or very nearly so; pedicels of the sterile flowers 1/2'-l' long; filaments dilated, mostly longer than the anthers, pubescent; achene narrowly obovate, 1 1/2"-2" long, winged on both margins, crested above, tipped with a stout nearly erect beak of about one-fourth its length.
In swamps and shallow water, Quebec to Minnesota, south to New Jersey, Tennessee, Missouri and Nebraska. Petioles rigid when growing in running water. July-Sept.
Monoecious, glabrous, scape slender, erect, simple, 6'-18' long, bearing only 1-3 verticils of flowers. Leaves usually reduced to elongated terete nodose phyllodia or some of them short and bract-like, one or two of the longer ones occasionally bearing a linear blade; bracts ovate, obtuse, about 1 1/2" long, much shorter than the filiform fruiting pedicels which are longer than the sterile ones; flowers 6"-8" broad; stamens about 12, their dilated filaments pubescent, shorter than the anthers; achene broadly obovate, 1" long, the ventral margin winged, the dorsal 7-11-crested, the sides bearing several crenate crests, the beak short, erect.
In ponds, Massachusetts to South Carolina. Aug.-Sept.