MICROSCOPIC STRUCTURE OF WEED SEEDS 



573 



Fig. 437. Microscopic structure of fruit of Bedstraw (Galium aparine). 



ep=epidermis. t=testa. t' =trichome. en=€ndosperm. 



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



CUCURBITACEAE, GOURD FAMILY. 



Wild Cueumber {Sicyos angulatus L.). 



The testa of the brownish seeds consists of elongated epidenmai 

 cells with narrow cell cavities; walls thickened, with pore canals. 

 The underlying portion consists of a layer of one or two rows of 

 cells with thin walls, and protein contents; the remaining portion 

 of the testa is composed of thin-walled cells with large inter- 

 cellular spaces. The related species, Echinocystis lobata, contains 

 a thick, pigment layer of brownish sclerotic parenchyma followed 

 by a thinner layer of thick-walled cells with blackish brown pig- 

 ment. In this species, as in Sicyos angulatus, frequently portions 

 of the fruit adhere to the surface. The seed coats of this family 

 have been described by Harz. 



