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 eurycarpum Engelm. in A. Gray, Man. Ed. 2, 430. 1856.
Stem stout, 3°-8° high, branching. Leaves linear, flat, slightly keeled beneath, the lowest 3°-S° long; staminate heads numerous; pistillate heads 2-4 on the stem or branches, sessile or more commonly peduncled, hard, compact and io"-i6" in diameter; style 1; stigmas 1-2; nutlets sessile, 3"-5" long, obtusely 4-5-angled, narrowed at the base, the top rounded, flattened or depressed, abruptly tipped with the style; scales as long or nearly as long as the fruit, often with 2 or 3 other exterior ones, somewhat spatulate, the apex rounded, denticulate or eroded.
Sparganium simplex androcladum Engelm.; A. Gray, Man.
Ed. 5, 481. 1867. Sparganium androcladum Morong, Bull. Torrey Club 15:
78. 1888. Sparganium americanum androcladum Fernald & Eames, Rhodora 9: 87. 1907.
Stem branching, 1°-3 1/2° high; leaves 1 1/2°-3 1/2° long, triangular at the base; bracts similar to the leaves, bases slightly dilated, and but narrowly scarious-mar-gined; inflorescence branched; branches and peduncles axillary, branches zigzag; fruiting heads 6"-12" diameter; nutlets brown, dull, fusiform, 2. 1/2"-3" long, terete or obtusely angled, often constricted at the middle; stigma linear, 1" long.
In bogs or shallow water, Newfoundland to Minnesota, Florida and Louisiana. June-Aug.
Sparganium americanum Nutt. Gen. 2: 203. 1818. Sparganium simplex Nuttallii Engelm.: A. Gray, Man. Ed. 5, 481. 1867.
Stem simple or nearly so, 1°-2 1/2° high; leaves 1°-3 1/2° long, keeled, somewhat scarious-margined near the base; bracts, at least the lower ones, similar to the leaves, but shorter, dilated and scarious-margined near the base; inflorescence usually simple, with the heads sessile, or the lower pistillate ones peduncled, the branches, when present, straight; fruiting heads 9"-12" in diameter; nutlets brown, dull, fusiform, 2V-3" long; stigma oblong, seldom over 1/2" long.
In low grounds or ponds, Nova Scotia and Ontario to Iowa, South Carolina and Oklahoma. June-Aug.
Sparganium lucidum Fernald & Eames, Rhodora 9:
Stem stout, 2°-3 1/2° high; leaves 1°-2° long, strongly keeled, 1 1/2"-6" wide; bracts similar to the leaves but shorter; inflorescence simple or somewhat branched, with the branches, or heads, axillary, the main axis bearing 2-4 sessile pistillate heads and 6-10 staminate heads, the branches, when present, bearing 1 pistillate head and sometimes 1-4 staminate heads; fruiting heads about 15" in diameter; nutlets olive-brown, shining, the body fusiform, about 4" long; stigma linear, 1 1/4"- 1 3/4" long.
In ponds and streams, Massachusetts to New York, Illinois and Missouri. July-Sept.