SECTION IV. 

 m 



BRYOPHYTA. 



-ff 



Mosses. 



The Mosses, of which there are more than six hundred British species (excluding 

 varieties and the Sphagnacece), belong to the sub-kingdom Bryophyta, together 

 with the Liverworts, and though so minute and apparently insignificant, play 

 quite an important part in the economy of Nature. It has been said that 

 at least a quarter of the vegetation covering the surface of Great Britain is 

 formed by one genus of moss alone. In any case, the mosses are the first 

 things to grow on any virgin soil, whether it be new-turned earth or a new- 

 built wall ; and by their decay the first fragments of soil are formed upon 

 which other and higher plants can germinate. Peat is the accumulated 

 debris of countless successions of moss plants. Many a mighty tree has begun 

 its life in the shady moisture of a moss bed, and in after years has repaid its 

 debt by offering to other mosses a habitation on its trunk and branches. 



Much of the work of the student of mosses can be done in the winter 

 season, for it is in winter and in early spring at least in low-lying districts 

 that they appear in their greatest beauty in " flower " and " fruit." 



The moss plant is a very minute thing, and needs a lens to make out its 

 characteristics. It consists of a stem, single or branching, with tiny leaves 

 clustering closely about it, sometimes bright green, yellow, red, purple, or 

 brown. The leaves are stalkless, and may be simple, thickened, or toothed, 

 with a single or forked midrib, in some cases projecting like a bristle from the 

 tip of the leaf. 



Under the microscope the leaves are seen to be made up of a single layer 

 of cells, in definite patterns, varying in the different species, and these form 

 important means of identification, the character being known as " areo- 

 lation." 



Mosses have little or no roots, although in some species a few slender 

 fibres may be found ; in others a compact woolly mass of them, which are 

 probably not roots but anchors holding the plant securely to its resting-place. 

 But this is a vexed question. 



They are usually considered as flowerless plants, but they have organs 

 which closely resemble flowers and may be found sometimes at the end of 



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