thallophyta

Thallophyta

Thal*loph"y*ta\, n. pl. [NL. See Thallophyte.] (Bot.) A phylum of plants of very diverse habit and structure, including the alg[ae], fungi, and lichens. The simpler forms, as many blue-green alg[ae], yeasts, etc., are unicellular and reproduce vegetatively or by means of asexual spores; in the higher forms the plant body is a thallus, which may be filamentous or may consist of plates of cells; it is commonly undifferentiated into stem, leaves, and roots, and shows no distinct tissue systems; the fronds of many alg[ae], however, are modified to serve many of the functions of the above-named organs. Both asexual and sexual reproduction, often of a complex type, occur in these forms. The Thallophyta exist almost exclusively as gametophytes, the sporophyte being absent or rudimentary. By those who do not separate the Myxophyta from the Tallophyta as a distinct phylum the latter is treated as the lowermost group in the vegetable kingdom.
Webster's Revised Unabridged Dictionary, © 1996, 1998 MICRA, Inc.
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WordNet
thallophyta

noun
used only in former classifications: comprising what is now considered a heterogeneous assemblage of flowerless and seedless organisms: algae; bacteria; fungi; lichens 
WordNet® 3.0, © 2006 by Princeton University.
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