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1 9 1°] EDWA RDS—HED YOSM UM 4 2 1 



Other peculiarities of endosperm development, however, such 



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more constantly throughout large groups than such features as a 

 single type of tapetum or embryo sac, or of a particular number 

 of potential megaspores. These peculiarities, therefore, may have 

 considerable weight in determining such broader relationships. 



Summary 



1. The staminate flowers usually occur in long-stalked ovoid 

 catkins which arise in a pair at the base of the cymelike female 

 inflorescence. Each stamen possesses 4 distinct microsporangia. 



2. The carpellate flowers occur in sparsely flowered panicles. 

 They have a single pistil, although there is some evidence that 

 3 carpels enter into the formation of this pistil (5). The perianth 

 of the female flower is initiated before the carpel. It is connected 

 with the surface of the ovary by means of a narrow longitudinal 

 band of tissue which extends along each of its 3 corners; by a 

 similar narrow zone about its base; and by another zone of attach- 

 ment around the ovary in the apical region just below the base 

 of the style. The perianth persists in the mature fruit and proba- 

 bly constitutes an added protection to the seed. 



3. The ovary is i-celled. Its wall is composed of 15 layers of 

 cells of which the epidermis and the next 3 layers within it are 

 small and but slightly thickened. The cell walls of the fifth, sixth, 

 and seventh layers adjoining the 4 just mentioned are at first 

 unevenly thickened, then, during the ripening of the seed, the 

 entire cavity of each of the cells becomes filled. The inner layer 

 of cells of the ovarian wall next the seed is also considerably thick- 

 ened in the ripe seed. These 3 thickened layers form the chief 



protection of the ripe seed. 



4- The ovule is pendulous and orthotropic. It bears 2 integu- 

 ments, the inner being the longer from the outset of development. 

 These are quite thick in the mature seed around the micropylar 

 region, but elsewhere they are unthickened and are scarcely dis- 

 coverable in the mature seed. 



5. A primary archesporium arises from a hypodermal cell of 

 the nucellus, which by dividing produces a tapetal cell and a 





