. An illustrated flora of the northern United States, Canada and the British possessions, from Newfoundland to the parallel of the southern boundary of Virginia, and from the Atlantic Ocean westward to the 102d meridian. Botany; Botany. 5° ISOETACEAE. Vol. 1. Family n. ISOETACEAE Underw. Native Ferns, 104. 1881. Aquatic or marsh plants rooting in the mud, with a short buried 2-lobed or 3-lobed trunk (stem) sending out abundant roots and sending up a compact tuft of rush-like leaves. Sporanges sessile in the axils of the leaves, some containing megaspores (megasporanges), others microspores (mi

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. An illustrated flora of the northern United States, Canada and the British possessions, from Newfoundland to the parallel of the southern boundary of Virginia, and from the Atlantic Ocean westward to the 102d meridian. Botany; Botany. 5° ISOETACEAE. Vol. 1. Family n. ISOETACEAE Underw. Native Ferns, 104. 1881. Aquatic or marsh plants rooting in the mud, with a short buried 2-lobed or 3-lobed trunk (stem) sending out abundant roots and sending up a compact tuft of rush-like leaves. Sporanges sessile in the axils of the leaves, some containing megaspores (megasporanges), others microspores (microsporanges) ; the former germinate into prothallia bearing only archegones, the latter into prothallia bear- ing usually only a single antherid. 1. ISOETES L. Sp. PI. 1100. 1753. Submerged, amphibious or uliginous plants with a cluster of elongated awl-shaped leaves rising from a more or less 2-3-lobed fleshy short stem, the leaves with or without peripheral bast-bundles, with or without stomata, bearing a small membranous organ (ligule) above the base. Sporanges sessile in the excavated bases of the leaves, orbicular or ovoid, the sides more or less covered with a fold of the inner side of the leaf-base (velum). The sporanges of the outer leaves usually contain spherical, mostly sculptured macrospores, those of the inner ones contain minute powdery usually oblong microspores. [Name Greek, taken from Pliny, apparently referring to the persistent green leaves.] The family consists of the following genus only. About 60 species, widely distributed. Besides the following 2 are known from the southern United States, 7 from the Pacific Coast and 2 from Mexico. Owing to their aquatic habitat and apparently local distribution, these plants are popularly little known. The spores mature in summer and autumn. Type species : Isoetes lacustris L. Leaves without peripheral bast bundles. Leaves without stomata ; plants submerged. Leaves stiff and erect. 1. /. macrospora. Leaves slender and