CLASSIFICATION OF ANGIOSPERMS. 



263 



and rather long petiole. The flowers have a 6-parte(l, dark green 



O 



^ O" a 



Fig. 138. Bnckwhea.*. (Fagopyrum esculentum) : A, transverse section of grain showing 

 pericarp (c), endosperm (n) and slender coiled embryo (e) ; B, transversesection of portion 

 of grain showing epicarp (e) , fibrous layer Cf ) , pigment layer (p) , outer epidermis of spermo- 

 derm (o), aleurone cells (a), endosperm cells containing starch (n); C, surface view of cells 

 of epicarp; D, isolated fibers of pericarp; E. surface \-iew of aleurone. cells; F, isolated par- 

 enchytpa cells of endosperm filled with starch grains as seen in buckwheat flour; G, appear- 

 ance of starch grains when mounted in oil and viewed with polarized light;_ H, swollen and 

 altered starch grains which are two to three times the size of the normal grains. 



perianth, and are perfect or polygamo-dioecious. The fruit is a 

 dark brown, cordate-winged, 3-angled akene. The dried root 



