14 FLOWERLESS PLANTS 



gradual drying up of the world. It is a fact 

 of supreme importance that the act of fertili- 

 sation in the case of practically all the flowerless 

 plants is carried on under water. This moisture 

 may be little more than a film of dew, as will 

 be seen later in the case of the mosses, but 

 the presence of moisture nevertheless remains 

 an essential feature. In the steamy forests of 

 the Coal Age there was an abimdance of moisture 

 which is not to be found save in a few tropical 

 jungles at the present time. Hence the area of 

 land which is suitable for a strong race of 

 flowerless plants is steadily decreasing with the 

 ages. 



So far as actual numbers are concerned, the 

 fungi and bacteria are vastly a greater group 

 than that of any other flowerless plant, number- 

 ing as they do nearly 40,000 known species. 

 The next largest group is that of the algae, 

 which in their many forms are not far short of 

 15,000 ; whilst the mosses and liverworts would 

 probably be about half of this number. The 

 lichens, which are still classed as species, albeit 

 each plant is a combination, are to be found 

 in well over 5,000 forms, whilst last of all 

 come the vascular cryptogams (ferns, club mosses 



