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Aquatic and Wetland Vascular Plants of the Northern Great Plains

Vascular Cryptogams, Ferns and Fern Allies

Perennial herbs with a life cycle featuring an alternation of two distinct generations -- the sporophyte and the gametophyte. Sporophyte the dominant phase, diploid, typically differentiated into vascularized roots, stems and leaves, producing unicellular, haploid spores by meiosis, the spores produced in sporangia which may be grouped in sori on modified or unmodified leaves, or the sporangia borne in terminal cones (Equisetum), spikes (Ophioglossum) inside axillary sporocarps (Marsilea and Azolla), or inside the leaf bases (Isoetes). Sporophyte plants may produce spores of all one type (plants homosporous) or of 2 morphologically dissimilar types (plants heterosporous), small microspores and larger megaspores. Spores germinating in soil or water to produce the minute, inconspicuous sexual phase, the gametophyte. Gametophyte (termed a prothallium) photosynthetic or achlorophyllous; gametophytes of homosporous species similar, monoecious or dioecious, those of heterosporous species dissimilar, dioecious, each microspore producing a male gametophyte, each megaspore producing a female gametophyte. Sex organs developing on the gametophytes; antheridia producing numerous motile spermatozoids; archegonia each containing an egg cell. Fertilization achieved by impregnation of an egg by a spermatozoid, subsequent growth from the fertilized egg resulting in development of the dominant sporophyte plant.


Pelvit, J. and W. T. Barker. 1975. North Dakota ferns and fern allies. Tri-
     College Center for Environmental Studies Publ. Ser. 1:1-24.

Petrick-Ott, A. J. 1974. A county checklist of the ferns and fern allies of 
     Kansas, Nebraska, South Dakota and North Dakota. Rhodora 77:478-511.

Tryon, R. M. 1954. The ferns and fern allies of Minnesota. Univ. of Minnesota 
     Press, Minneapolis.

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