34 PLANT LIFE. 



structures directly or indirectly concerned with the pro- 

 duction of seeds or spores, which are for the purpose of 

 producing new individuals, and thus providing for the con- 

 tinuance of the species in time. Such structures do not in 

 any way assist the plant producing them, as an individual, 

 but on the other hand are a great tax on its energies. The 

 division of labour as illustrated between the vegetative and 

 reproductive portions is usually sharply marked in the case 

 of the higher plants. Taking the apple tree as an illustration 

 we may say in general terras that the root, trunk, branches, 

 and leaves constitute the vegetative part, or all that is 

 required for the life of the individual tree ; whereas the 

 flowers or reproductive portions are, even to the casual 

 observer, abruptly different in general appearance, and sug- 

 gest the idea of being as it were something tacked on to the 

 older vegetative part, and this idea is correct in the sense of 

 the sharply differentiated sexual parts when compared with 

 older and simpler types of plants. In the majority of 

 flowering plants living at the present time, the very varied 

 contrivances presented by the flower as popularly under- 

 stood, for securing cross-fertilization, protection, dispersion 

 of the seed, etc., are evolved characters and not con- 

 temporaneous with the vegetative parts producing them at 

 the present day. The vegetative portions of plants have also 

 undergone marked changes from time to time, but not 

 perhaps equal to those connected with the sexual method of 

 reproduction alluded to above, which in flowering plants 

 has, owing to its many advantages, almost entirely and in 

 numerous instances altogether superseded the old asexual 

 or vegetative mode of reproduction. 



Cell-formation in the reproductive parts of plants is 

 characterized by the contraction and rounding of the 



