CHAPTER XXIV 



SPERMATOPHYTES : ANGIOSPEEMS 



207. Summary of Gymnosperms. — Before beginning An- 

 giospernis it is well to state clearly the characters of Gym- 

 nosperms which have set them apart as a distinct grouji of 

 Spermatophytes, and which serve to contrast them with 

 Angiosperms. 



(1) The micros^oore (pollen-grain) by wind-p)ollination 

 is brought into contact with the megasporangium (ovule), 

 and there develops the pollen-tube, which penetrates the 

 nucellus. This contact between jiollen and ovule implies 

 an exposed or naked ovule and hence seed, and therefore 

 tliu name '' Oymnosperm." 



(2) Tlie female gametopliyte (endosperm) is well organ- 

 ized before fertilization. 



(3) The female gametopliyte produces archegonia. 



238. General characters of Angiosperms. — Tliis is tlie great- 

 est group of plants, both in numbers and importance, being 

 estimated to contain about 100,000 species, and forming 

 the most conspicuous part of the vegetation of the earth. 

 It is essentially a modern group, replacing the Gymnosperms 

 which were formerly the dominant Seed-plants, and in tlie 

 variety of their display exceeding all other groups. The 

 name of the group is suggested by the fact that the seeds 

 are inclosed in a seed case, in contrast with the cxjiosed 

 seeds of the Gymnosperms. 



These are also the true flowering plants, and the ap- 



jiearance of true flowers means the development of an 

 358 



