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A green, filamentous structure that originates from an asexual spore of mosses and some liverworts and that gives rise by budding to a mature plant.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



in mosses, part of the gametophyte that develops from the spores (primary protonema) or from the rhizoids, stems, and leaves (secondary protonema). The protonemata of leafy mosses are shaped like ramose green threads; those of liverworts and sphagnum mosses are poorly developed and platelike. Buds arise on the protonemata and develop into leafy shoots that bear antheridia and archegonia (gametophores). The protonema usually dies shortly after its development, but sometimes (for example, in the moss Buxbaumia) it remains throughout the plant’s entire life.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.