The protonema forms a flat, lobed, thalloid structure attached to the soil by rhizoids, and the plants arise from marginal cells.
They often merge insensibly into the green filaments (protonema) already noticed.
The formation of the moss-plant on the protonema is always from a single cell and is similar in all mosses.
Usually the protonema is filamentous and ceases to be evident after the plants have developed.
This tangled mass of green threads, called the protonema, is the first growth, from which the moss stems spring.
In Ephemerum also we may probably regard the relation of the small plants to the protonema as a primitive one.
The protonema is not persistent, and the plants are well developed, resembling those of Pleuridium.
In mosses (fig. 12) a filamentous growth, the protonema, is first formed, and the leafy plants arise upon this.
Erect branches may arise from the protonema, and gemmae may be developed on it.
The protonema is always a well-marked stage in the life-history.