178 BOTANY. [CHAP. v. 



The species are trees or shrubs, herbaceous species 

 being absent. Finally, all are anemophilous, or wind- 

 fertilized. 



II . Angiosp ermece . 



Fibro-vascular bundles either closed and scattered or 

 open and arranged concentrically. Ovules developed 

 within the cavity formed by closed carpellary leaves; 

 fertilization consequently indirect, the pollen being re- 

 ceived on the stigma, where it forms a pollen-tube that 

 eventually comes in contact with the ovule. 



Angiosperms as a group include the latest or most 

 modern types of plant evolution, and embody in many 

 groups the relative perfection of structure and adapta- 

 tion to circumstances which has taken geological ages 

 to evolve. The outcome of this evolution shows itself 

 in the elimination of many antiquated structures that 

 performed perfectly the functions required, but at too 

 great an expenditure of energy and material, and in all 

 the most highly differentiated groups, the outcome of 

 unconscious evolution tends towards one grand idea, 

 that of securing the greatest benefit with the least 

 possible outlay. Angiosperms include all flowering 

 plants, with the exception of the cycads and conifers, 

 enumerated under Gymnosperms; the various members 

 present all grades, from the tiniest wayside weed to 

 the forest tree, and in point of duration from a single 

 season to that of a period extending over centuries. 

 Wind-fertilization and self-fertilization are both still in 

 vogue, but in the great majority of species, insect- 

 fertilization is more or less completely relied upon, and 

 the enormous variety of floral evolution in connection 



