154 Plant Life and Evolution 



there may be 50 or more nuclei at the time of fer- 

 tilization. In all of these genera, which are usually 

 considered to be primitive types, the occurrence of 

 these different forms of embryo-sac is interesting, 

 as it suggests, at least, a condition intermediate 

 between the embryo-sac of the typical angiosperms 

 and that found in some lower type, possibly a form 

 like Gnetum. 



It must be borne in mind that this microscopic 

 body within the embryo-sac, composed of eight cells, 

 and the still more rudimentary structure developed 

 from the germinating pollen-spore, are all that re- 

 main of the sexual plants or gametophytes, which 

 in the lower archegoniates are so conspicuous. In 

 the angiosperms the plant, as we ordinarily think 

 of it, is the strictly non-sexual sporophyte. The 

 stamens and carpels are not the sexual reproductive 

 organs, the latter being really represented by the 

 rudimentary archegonium in the embryo-sac and the 

 very simple antheridium in the pollen-spore, which 

 correspond to the sexual organs in the mosses and 

 ferns. 



Flowers of the Lower Angiosperms. In many 

 of what are usually considered the most primitive 

 angiosperms, e.g., willows, poplars, bur-reeds, 

 screw-pines, and others, the flowers are diclinous, 

 that is, stamens and carpels are in different flowers, 

 and often upon different plants. The flower may 

 even be reduced to a single carpel or stamen, and 

 the floral envelopes, which are so striking a feature 



