MICROSCOPIC STRUCTURE OF WEED SEEDS 



573 



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



ep=epidermis. t=testa. t 1 =trichome. en=endosperm. 



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



CUCURBITACEAE, GOURD FAMILY. 



Wild Cucumber (Sicyos angulatus L.) 



The testa of the brownish seeds consists of elongated epidermal 

 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. 



