167 



CHAPTEE VI. 



Group IV. 

 SPEBMAPHYTA OB PHANEROGAMIA.' 



This group of plants, so long considered as one standing apart 

 from and above all others, or corresponding in classiiioatory 

 value to the whole of the Cryptogams, is now held to be properly 

 only upon an equal footing with the other groups already dis- 

 cussed. The gradual increase of complexity of structure of 

 the sporophyte, associated with the progressive degradation of 

 the gametophyte, reaches its maximum in this group, which 

 appears as the fourth member of the series into which the 

 Vegetable Kingdom is now divided. 



The heterosporous character of the sporophyte, which we 

 have seen to appear irregularly in the Pteridophyta, is here 

 constant. The microspores are developed in much the same 

 way and in about the same numbers as in the latter group ; the 

 macrospores show a considerable degradation, and the macro- 

 sporangia never become free from the parent plant until some 

 time after their gametophytes are mature, not indeed until the 

 young sporophyte or embryo produced by each of the latter has 

 attained a considerable degree of development. The result is 

 that a peculiar structure known as the seed makes its appearance 

 for the first time in this grotip of plants. As its development 

 shows some variability, it will be well, for the present, to defer 

 its consideration. On account of its constant occurrence, the 

 group is sometimes called the Spcrmaphyta. 



The general morphology and anatomy of the group have 

 formed the subject of the greater part of the first two sections of 

 this manual, and need not, therefore, be treated of at length in the 

 presentjfesipter. 



""The chief remaining points calling for attention in connection 

 with the Phanerogams are the structure of the sporophylls ; the 

 development of their sporangia, and spores ; the gametophyte 

 generation ; and the embryogeny of the sporophyte. 



