Mosses and Lichens 



thallose plants, and its position is not only intermediate from a 

 structural standpoint, but in its relation to the evolution of the 

 higher plants it stands as a key or link between the lower or 

 simpler, and the higher or more complex. 



"The hepatics possess almost no utilitarian aspect. Beyond 

 the doubtful use of one or two for medicine, and the occasional 

 occurrence of one or more tropical species as weeds, they are, so 

 far as the physical condition of the human race is concerned, an 

 entirely useless group of plants . . . and yet from the higher 

 standpoint of genetic relationship, there is probably no single 

 group of plants that occupies such a unique position in the plant 

 world. What the group 'Vermes' is to the animal kingdom, 

 the Hepaticce are to plants, with this difference, that we have here 

 a much less complicated group of organisms with which to deal." 



MINUTE STRUCTURE 



To understand the relation of this plant group it is necessary 

 to have some knowledge of the microscopic structure of a 

 developing moss plant, both liverwort and leafy-moss, and a 

 knowledge of plants less and more complicated in structure than 

 the mosses. This knowledge can to a certain degree be acquired 

 by a study of somewhat diagrammatic drawings of magnified 

 sections of algae, mosses and ferns. If after this preliminary 

 knowledge has been acquired, an opportunity occurs to see the 

 sections themselves under a compound microscope, the interest 

 will be intensified. 



PROTONEMA 



As was stated, a germinating moss or hepatic spore results 

 in a single cell or a group of cells (protonema.} A part of the cells 



....".Moss-pla-nt* 



Sphagnum cymbifolium. First or sexual generation. 



of the more elaborate protonema are without leaf-green (chloro- 

 phyll) and seek the darkness afforded by the structure of the 



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