460 The Living Plant 



ground. But in fact there is every gradation between them, and 

 one answers morphologically to the other in a manner most 

 striking and satisfactory, though it is not any part of my business 

 at present to explain the matter more fully. But there is one 

 thing about this pollen-tube arrangement that is of greatest 

 evolutionary importance, viz., it has rendered these plants in- 

 dependent of standing water and a prothallium on the ground for 

 their fertilization, and has thus freed them from the restriction 

 which limits the range of the Fern-plants. Hence the Flowering 

 Plants are able to extend over places too dry for the Fern-plants, 

 and indeed over all parts of the earth where plant-life is a possi- 

 bility at all; and not only that, but through virtue of their higher 

 organization in other respects they are able to compete with the 

 lower groups, the Undergrowth plants, the Carpet plants, the 

 Parasitic plants, and the Water plants, in their own peculiar 

 situations, of which they are slowly but surely taking possession 

 in the course of their evolution. And the best evidence of their 

 success is found in their numbers, for they have been able to 

 develop no less than some one hundred and thirty-three thousand 

 distinct species already known and named, many more, it will 

 be noted, than of all the other groups put together. 



The Flowering Plants include two very distinct groups. First 

 are the Gymnosperms, Pines, Spruces, Firs, and that sort, 

 which are trees and tall shrubs without any flowers, and bearing 

 their seeds naked on the branches, or partly covered by cone- 

 scales; and they are almost wholly wind-disseminated and wind- 

 pollinated. Second are the Angiosperms, with their seeds en- 

 closed always in an ovary which is part of a flower. Some of 

 them, the Oaks, Chestnuts, Beeches, Elms, Birches, Alders, and 

 such kinds, are trees or tall shrubs, wind-pollinated (and there- 

 fore without showiness in the flowers) and wind-disseminated. 

 The remainder fall into two sub-groups, Dicotyledonous or Ex- 

 ogenous Plants, which appear to occupy the main line of advance, 

 and Monocotyledonous or Endogenous Plants, which seem to 



