The spores are set free by the bursting of their chamber, and each germinates, putting out a branched thread of cells called a protonema, which may perhaps properly be termed a third generation in the cycle of the plant; for it is only from buds developed on this protonema that the leafy sexual plant arises. ❋ Various (N/A)
Besides this, gemmae may be formed on the protonema, on the leaves or at the apex, and some mosses have specialized shoots for their better protection or distribution. ❋ Various (N/A)
In _Ephemerum_ also we may probably regard the relation of the small plants to the protonema as a primitive one. ❋ Various (N/A)
Erect branches may arise from the protonema, and gemmae may be developed on it. ❋ Various (N/A)
The protonema is always a well-marked stage in the life-history. ❋ Various (N/A)
The protonema forms a flat, lobed, thalloid structure attached to the soil by rhizoids, and the plants arise from marginal cells. ❋ Various (N/A)
In _Sphagnum_, _Andreaea_ and some genera of the Bryales the protonema or some of its branches have the form of flat plates or masses of cells. ❋ Various (N/A)
The protonema is not persistent, and the plants are well developed, resembling those of _Pleuridium_. ❋ Various (N/A)
In addition to the leaves the stem often bears hair-like structures of different kinds, some of which correspond to modified branches of protonema. ❋ Various (N/A)
The protonema is usually filamentous, and in some of the simplest forms is long-lived, while the small plants borne on it serve mainly to protect the sexual organs and sporogonia. ❋ Various (N/A)
With one or two exceptions, however, this preliminary [v. 04 p. 0648] phase, which may be compared with the protonema of mosses, is of short duration. ❋ Various (N/A)
In this moss the filamentous protonema is capable of assimilation, but the leaves of the small plants are destitute of chlorophyll, so that they are dependent on the protonema. ❋ Various (N/A)
The social growth of the plants characteristic of many mosses is a result of the formation of numerous plants on the original protonema and on developments from the rhizoids. ❋ Various (N/A)
The formation of the moss-plant on the protonema is always from a single cell and is similar in all mosses. ❋ Various (N/A)
The spore on germination forms a short filament which soon broadens out into the thalloid protonema. ❋ Various (N/A)
The sexual generation is always a leafy plant, which is not developed directly from the spore but is borne on a well-marked and usually filamentous protonema. ❋ Various (N/A)
The indications of a serial progression are not so clear in the mosses, but the majority of the forms may be regarded as forming a great phylogenetic group in the evolution of which the elaboration of the moss-plant has proceeded until the protonema appears as a mere preliminary stage to the formation of the plants. ❋ Various (N/A)
The moss-plants arise from single projecting cells, and numerous plants may spring from the protonema developed from a single spore. ❋ Various (N/A)
A filamentous protonema is first developed, some of the branches of which are exposed to the light and contain abundant chlorophyll, while others penetrate the substratum as brown or colourless rhizoids. ❋ Various (N/A)
Vegetative propagation is widely spread in the mosses, and, as mentioned above, a protonema is always formed in the development of the new plant. ❋ Various (N/A)
