78 



CR YP TOGA MO US T YPES. 



develops pi-othallia upon which archegonia are formed, 

 ;uul tlie smaller others upon wliicli antheridia appear. 

 Tlie three plants just considered, while evidently differing in 

 certain details of structure and in general aspect, never- 

 theless have a number of characters in common : 



1. They acjree in their mode of reproduction, tvhich is hy 



nj)ores, these bodies being quite unlike the seeds ^v^fh 

 which we are noto familiar, and ichieh, you will 

 recollect, always contain the embryo of the new plant. 



2. They all exhibit an alternation of generations. 



3. They all have true roots. 



4. The three tissue-systems — the epidermal, the fibi^o-vascu- 



lar. and the fundamental — though not all developed to 

 so high a degree as in the Phanerogams, still can be 

 very clearly made out in both roots and stems. The 

 fibro-rascular bundles are alicays closed, as in mono- 

 cotyledons, and are, as a general rule, co7icentric. 

 Plants with these common characteristics constitvite a gi'oup 

 called Pteridophytes or Vascular Cryptogams, "crypto- 

 gam " being a general term applicable to all plants which 

 do not produce true flowers, as ' ' phanerogam " applies to 

 all those which'do. 



BRYOPHYTES. 

 Mosses. 



Fig. 304 is a representation of the common Hair-Moss {Poly- 

 trichum commune), which may be found in early sum- 

 mer almost anywhere. It grows in dense masses, and 

 upon examination it will be found that while many of 

 the stems resemble that shown in Fig. 304, the upper 

 extremities of the others form rosettes, as in Fig. 305, 

 whilst others again terminate in ordinary vegetative 

 buds. 



Let us first examine a specimen as represented in Fig. 304. 

 There is, it will be observed, a well-marked stem, or leaf- 

 bearing axis, upon which the crowded minute leaves are 

 sessile. In the Mosses they always are so, and they are 

 found, upon examination with a good microscope, to con- 

 sist as a rule of only one layer of cells, being therefore 

 much simpler in construction than those of the plants we 

 have so far been engaged upon. It is also to be noticed 

 that the leaves of Mosses are without stomata. 



Observe now that our Moss has no true roots. It is, however, 

 fixed to the soil upon which it grows by numerous root- 

 hairs or rhizoids. 



The slender scape-like stalk which rises above the leaves is 

 technically called the .seta or bristle; in the left-hand i)art 

 of the figure (c) the upper end of tlie seta is covered by a 



Fiff. 304. 



Fig. 305. 



