Monographs Details: Marsilea
Authority: Mickel, John T. & Beitel, Joseph M. 1988. Pteridophyte Flora of Oaxaca, Mexico. Mem. New York Bot. Gard. 46: 1-580.
Description:Species Description - Aquatic or subaquatic, rooting in mud, underwater, at water edge, or in ephemeral pools; rhizome slender, long- to short-creeping, with hairs; fronds small, distant to close, monomorphic; stipe long, blade of four cuneate, flabellate leaflets terminal on stipe, glabrous to hairy, membranaceous; veins flabellate, forking, usually anastomosing slightly, especially near the margin; sporangia in nutlike sporocarps, at stipe base or on stipe, with two teeth near base, ridge (raphe) on end towards stalk present or absent; heterosporous, both micro- and megasporangia borne in gelatinous matrix in the sporocarp.
Discussion:Lectotype (chosen by Maxon, Pteridophyt. Porto Rico 509. 1926): Marsilea quadrifolia Linnaeus.
Zaluzianskia Necker, Hist. & Commentat. Acad. Elect. Sci. Theodor.-Palat. 3: 303. 1775, non Zaluzianskya F. W. Schmidt, 1793. Type: Zaluzianskia marsiloides Necker [=Marsilea quadrifolia Linnaeus].
Marsilea is a genus of about 70 species, with most species in Africa and Australia. The New World species have been recently monographed by Johnson (1986), and our treatment is based primarily on this work. Two species occur, rarely, in Oaxaca, with three species found both north and south of Oaxaca.
The Marsileaceae are possibly related to the Schizaeaceae but this tenuous connection is based on the very obscure annular cells being terminal on the sporangium.
Reference: Johnson, D. M. 1986. Systematics of the New World species of Marsilea (Marsileaceae). Syst. Bot. Monogr. 11: 1-87.