The World Flora Online

Plants aquatic or amphibious, rhizomatous. Stems growing on soil surface or subterranean, main stem long-creeping and giving rise to long or short shoots only at nodes; hairs laterally attached, multicellular. Roots arising at nodes and also along internodes. Leaves distichous, long-petioled, sometimes filiform and lacking expanded blades. Sori within hard bean- or pea-shaped bodies (sporocarps) arising on short stalks from near or at base of petioles. Sporangia of 2 kinds, borne within the same sorus and sporocarp; megasporangia containing a single megaspore; microsporangia containing 20--64 microspores. Gametophytes remaining within spores; microgametophytes of only a few cells; megagametophytes protruding from spores, each bearing 1 simple archegonium.

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Plants small, herbaceous, in shallow water or on shores of lakes and ponds. Rhizomes slender and creeping with a siphonostele, covered with short side-attached hairs or glabrous. Fronds linear or with 2-4 obtriangular or fan-shaped pinnae attached at top of stipe, these floating on water surface or emergent. Spores formed inside bean-shaped sporocarps attached to stipe by a short peduncle. Sporocarps containing 2-30 sori, each sorus including both megasporangia and microsporangia. Megasporangium with 1 large spore; microsporangium with 16-64 small spores.

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Herbs growing in water or wet places, with wide–creeping solenostelic, sometimes hairy rhizomes

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Small aquatic or semi-aquatic ferns with a creeping, branched, solenostelic rhizome

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Fougères aquatiques ou semi-aquatiques.\n\t\t\t\n\t\t\t\t Sporophytes'petits; rhizome rampant, ramifié, solénostélique.'Feuilles'à préfoliaison circinée, simples ou comprenant 2 ou 4 folioles opposées au sommet du pétiole; nervures ramifiées dichotomiquement et s'anastomosant.'Sporanges renfermés dans des sporocarpes fermés, ceux-ci étant insérés par de courts pédicelles sur les pétioles, souvent tout à la base de ceux-ci.\n\t\t\t\n\t\t\t\t Spores de 2 sortes : mégaspores solitaires, formées dans des mégasporanges, et microspores nombreuses, formées dans des microsporanges.\n\t\t\tGamétophytes ♀ multicellulaires.\n\t\t\tGamétophytes ♂ très petits.\n\t\t\tFamille subcosmopolite, groupant 3 genres et environ 70 espèces. Pour la Flore : 1 genre.

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SELECTED REFERENCES

Braun, A. 1871. Hr. Braun theilte neuere Untersuchungen über die Gattungen Marsilea und Pilularia. Monatsber. Königl. Preuss. Akad. Wiss. Berlin 1870: 653--753. Johnson, D. M. 1986. Systematics of the New World species of Marsilea (Marsileaceae). Syst. Bot. Monogr. 11: 1--87.

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