CHAPTER X 



ANGIOSPERMS ( J/CLVOCO TYLEDONS) 



THE second great division of the seed-bearing plants, 

 the Angiosperms, is preeminently the prevailing modern 

 plant type. These are the plants ordinarily thought of 

 as " flowering plants." They are at once distinguished 

 from the Gymnosperms by the development of a closed 

 ovary formed from the carpel, or by the union of two 

 or more carpels. Within this closed cavity are borne 

 the ovules or macrosporangia, which are usually, but 

 not always, outgrowths of the carpellary leaves. Some- 

 times the apex of the floral axis or shoot is transformed 

 directly into the ovule. 



The flowers of the Angiosperms exhibit extraordi- 

 nary variety, and contrast strongly with the very uni- 

 form character of the flowers of most Gymnosperms. 

 In the simplest types (Fig. 43) the flowers of the 

 Angiosperms are nearly as simple as the simplest 

 Gymnosperms, but as a rule they are far more complex. 

 This arises primarily from a multiplication of the 

 sporophylls, but is further complicated by the develop- 

 ment of accessory leaves, sepals and petals, never found 

 in the Gymnosperms. 



In most Angiosperms both sorts of sporophylls are 

 usually associated in the same flower; i.e. the flower 

 contains both carpels and stamens, which are sur- 

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