DIVISION II. 



THALLOPHYTA. 



CHAPTER XXL 



THALLOPHYTA. 



Introductory. 



The Angiosperms have been described in some detail in the preceding 

 Chapters. They form the chief constituent of the Flora of the Land, 

 and are recognised as the highest types of Plant-Life. But the 

 Gymnosperms, Pteridophyta, and Bryophyta are also prominent 

 features in Land-Vegetation. For instance large areas are covered 

 by Pine Forests : Ferns, Club-Mosses, and Horsetails are world-wide 

 in their spread : and Mosses and Liverworts are present in quantity 

 wherever there is sufficient moisture for them to nourish. These 

 large Divisions of the Vegetable Kingdom are held to occupy a middle 

 position between the highest and the lowest Plants. The consideration 

 of them will, however, be held over for the present, until that residuum 

 has been considered which remains after all of these have been excluded. 

 The residuum comprises the lowest and simplest of plant-organisms. 

 These are very numerous both in individuals, and in species and 

 genera. Individually they are often small and inconspicuous, and 

 many of them are dwellers in water. Nevertheless, on the basis 

 of their nutrition and of the encystment of their cells they are properly 

 ranked as Plants. They are collectively designated Thallophyta, 

 or thalloid Plants, since a general feature in them is the absence of 

 that differentiation of the shoot into axis and leaf which is charac- 

 teristic of the higher forms. They include the Algae, Fungi, and 

 Lichens. 



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