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..
Sparganium erection β L. Sp. PI. 971. 1753. Sparganium simplex Huds. Fl. Aug. ed. 2. 401. 1788.
Stem rather stout, 1 1/2°-2° high; leaves 1 1/2°-3° long, triangular-keeled, 4"-8" wide; bracts flat or slightly keeled; inflorescence usually simple, the pistillate heads 2-5, at least some of them supra-axillary, the lower 1 or 2 peduncled, the staminate heads 4-8; fruiting heads about 15" in diameter; nutlets brown or sometimes greenish-brown, the body fusiform, 2 1/2"-3" long, often constricted at the middle; stigma linear, about 1" long.
In lakes and streams, Quebec and Ontario, and in Washington and British Columbia. Also in Europe and Asia. July-Sept.
Sparganium chlorocarpum Rydb. N. A. Fl. 17': 8. 1909.
Stem slender, 1°-2° tall, or sometimes floating; leaves 1°-2° long, at least the middle ones keeled, 1 1/2"-3 1/2"wide; bracts similar to the leaves, slightly, if at all, dilated or scarious at the base; inflorescence simple, the pistillate heads 2-4, sessile or the lowest one peduncled, the staminate heads 3-7; fruiting heads 10"-12" in diameter: nutlets green, rather dull, the body fusiform, 2"-2i" long; stigma less than 1" long.
In marshes and rivers, western New York to Iowa and Indiana. July-Sept.
Sparganium diversifolium Graebner, Schrift. Nat. Ges. Danzig. II. 9: 335. 1895.
Stem rather stout, !°-3° high; leaves narrow, 1 1/2"- 2 1/2" wide, abruptly pointed, the lower ones flat, the upper ones convex on the back or sharply keeled near the base; bracts similar to the upper leaves; inflorescence simple, often nodding at the tip, the pistillate heads 1-3, distant, the staminate heads 1-6, distant; fruiting heads 10" in diameter; nutlets grayish-brown, the body prominently-nerved, obovoid; stigma linear-lanceolate.
In bogs, Newfoundland, New Hampshire and Minnesota. Also in Europe. July-Sept.
Sparganium simplex acaule Beeby; Macoun, Cat. Can.
PI. 5: 367. 1890. Sparganium diversifolium acaule Fernald & Eames, Rhodora 9: 88. 1907 Sparganium acaule Rydberg, N. A. Fl. 171: 8. 1909.
Stem rather slender, 1/3°-1° high; leaves very narrow, 1"-2" wide, triangular-keeled; bracts nearly similar to the leaves, but dilated and with broad scarious margins at the base; inflorescence simple, erect, the pistillate heads solitary or 2 or 3, and approximate, usually sessile, supra-axillary, the staminate 2-4, less crowded than the pistillate ones; fruiting heads 7"-8" in diameter; nutlets olive-brown, the body not nerved, fusiform, 1 1/2'-2" long.
In swamps and on muddy shores, Newfoundland to Iowa. South Dakota and Virginia. July-Sept.