MICROSCOPIC STRUCTURE OF WEED SEEDS 



563 



the compressed perisperm, brownish yellow in color. The endo- 

 sperm consists of thickish-walled, colorless parenchyma cells, the 

 outer row smaller than the underlying, the inner layer of smaller 

 elongated cells. The contents consist of protein and fat. The 

 inner epidermal cells of the embryo are smaller than the endo- 

 sperm cells; they contain protein and fat. 



CONVOLVULACEAE, CONVOLVULUS FAMILY. 



European Bindweed (Convolvulus arvensis L.). 



The testa consists of an outer row of short or elongated cells p 

 with thick walls and brownish contents. This is followed by a 

 layer of small cells with colorless walls. Contents brownish. The 

 Malphighian cells m are situated underneath. This is followed by 

 a layer of parenchyma cells consisting of 8-12 rows of cells. The 

 endosperm consists of thick-walled colorless cells. The walls in 

 part mucilaginous. 



Pig. 430. Microscopic structure of the seeds of Convolvulaceae. 

 I. Morning-glory (Convolvulus sepium). II. Cultivated Morning-glory (Ipomoea 

 purpurea). III. Dodder (Cuscuta epithymum) . IV. Bindweed (Convol- 

 vulus arvensis). 

 ep=epidermis. m=malpighian cells. ll=light line. p=parenchyma. n=nucellus. 

 en=endosperm. 



(Drawings by D. H. Pammel and Charlotte M. King.) 



