GROUP IV. PHANEROGAMIA. 



447 



does so in the form of an arch, so that the apex is not exposed 

 to injury whilst the member is forcing its way up through the 

 soil. 



Epigean cotyledons become green in colour, and in many cases 

 (e.g. Sunflower, Radish) assume the appearance, and discharge 

 the functions, of foliage-leaves ; but they do not ever precisely re- 

 semble, either in size or form, the true foliage-leaves of the plant 

 to which they belong. 



Vegetative Propagation is common, among Phanerogams, by 



c 



n 



FIG. 288. Germination of pollen-grain of Lilium Martagon (x750: after Guignard). A 

 Young pollen-grain: c centrospheres; n resting nucleus. B Commencement of germina- 

 tion : n the dividing nucleus ; c centrospheres. C Cell-formation has taken place, result- 

 ing in the formation of the generative cell g; n nucleus of remainder of pollen-grain (i.e. 

 vegetative cell). 



means of bulbs (e.g. Lily, Onion, and many other Monocotyledons), 

 tubers (Potato), tuberous roots (Dahlia), etc. 



B. THE GAMETOPHTTE. As all Phanerogams are heterosporous, 

 the sexual generation is represented by two individuals, a male 



v. s. B. GO 



