- a primary, usually filamentous structure produced by the germination of the spore in mosses and certain related plants, and from which the leafy plant which bears the sexual organs arises as a lateral or terminal shoot.
Origin of protonema
1855–60; < New Latin < Greek prōto- proto- + nêma thread
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
Examples from the Web for protonema
The protonema is always a well-marked stage in the life-history.
They often merge insensibly into the green filaments (protonema) already noticed.Elements of Structural and Systematic Botany
Douglas Houghton Campbell
In mosses (fig. 12) a filamentous growth, the protonema, is first formed, and the leafy plants arise upon this.
Usually the protonema is filamentous and ceases to be evident after the plants have developed.
The protonema forms a flat, lobed, thalloid structure attached to the soil by rhizoids, and the plants arise from marginal cells.
- a branched threadlike structure that grows from a moss spore and eventually develops into the moss plant
C19: from New Latin, from proto- + Greek nema thread
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
- The green filamentous or flat, thallus-like structure that grows from the germinated spores of liverworts and mosses and eventually gives rise to a mature gametophyte.
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