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..
Submerged or rarely above water in dry seasons; leaves 10-30, rigid, rather thick, scarcely tapering, dark or olive green, obtusely quadrangular, 2'-6' long; stomata none; peripheral bast-bundles wanting; sporange orbicular or broadly elliptic, unspotted; velum rather narrow; ligule triangular, short or somewhat elongated; macrospores 600-800 μ in diameter, marked all over with distinct or somewhat confluent crests, and bearing three converging ridges; microspores 30- 46 μ. long, smooth or papillose.
In 1°-5° of water, Labrador to the Northwest Territory, south to eastern Massachusetts and New Jersey. Formerly confused with Isoetes lacustris L., of the Old World.
Isoetes Tuckermani A. Br. in A. Gray, Man. Ed. 5,
676. 1867. Isoetes Tuckermani borealis A. A. Eaton, Fernwort Papers 10. 1900. Isoetes Harveyi A. A. Eaton, Fernwort Papers 11. 1900.
Submerged or rarely partly or wholly emersed during very dry seasons; leaves 10-40, very slender, tapering, olive-green, quadrangular, 2'-5' long, without peripheral bast-bundles, the outer recurved; sporange oblong, mostly white, its upper one-third covered by the velum; macroscpores 440-785 μ in diameter, with wavy somewhat parallel and branching ridges on the upper half, separated by the three converging ridges, the lower covered with an irregular network; microspores 26-42 μ long, nearly smooth, or with minute spines.
In ponds, Newfoundland to Massachusetts and Connecticut; clustered in shallow water.
Isoetes hieroglyphica A. A. Eaton, Fernwort Papers 10. 1900.
Submerged with a bilobed trunk. Leaves 10-20, 2 1/2'-3' long, blunt at the apex, without stomata; sporange spotted with dark cells, covered one-third to two-thirds by the velum; macrospores 486-720 μ in diameter, polished, covered with bold vermiform, subconfluent and somewhat reticulated ridges, becoming naked near the equator; microspores 31-44 μ in diameter, distinctly verrucose.
Nova Scotia to Quebec and Maine; usually growing in ponds and lakes.
Isoetes Braunii Durieu, Bull. Soc. Bot. France, 11: 101.
1864. Isoetes echinospora var. Braunii Engelm. in A. Gray,
Man. Ed. 5, 676. 1867. Isoetes echinospora Boottii Engelm. in A. Gray, Man. Ed.
5, 676. 1867. Isoetes echinospora robusta Engelm. Trans. St. Louis
Acad. 4: 380. 1882. Isoetes echinospora muricata Engelm. in A. Gray, Man.
Ed. 5, 676. 1867.
Submerged or in dry seasons emersed, leaves 10-70, tapering, soft, green. 3'- 12' long, without peripheral bast-bundles, bearing stomata only toward the tip; sporange orbicular or broadly elliptic, spotted, one-half to three-fourths covered with the velum; macrospores 400-620 μ in diameter, covered with broad spinules which are often slightly confluent and incised at the tips; microspores 25-32 μ long, smooth.
Labrador and Greenland to Alaska, south to New Jersey, Pennsylvania and California.