570 



WEED FLORA OF IOWA 

 SOROPHULARIACEAE, PIGWORT FAMILY. 



Mullein {Veriascum thapsus L.)- 



The minute, roughened seeds are irregular, 

 are dark colored, longer than broad and thick 

 mal layer is followed by one or more layers 

 more numerous in the micropilar region; an 

 pressed layer with large intercellular spaces 

 sponding to the irregularities on the surface, 



The epidermal cells 

 walled. The epider- 

 of parenchyma cells, 

 indistinct and corn- 

 follows, these corre- 

 smaUer intercellular 



Fio. 435. Microscopic structure of the seeds of the Flgwort family (Scropftul- 



ariaceae). 

 I Moth Mullein (.Veriascum hlattaria). II. Common Mullein (.Verbaacum 



thapsua). 

 ep=epidermis. p=parenchyma. al=aleurone layer. en=endosperm. em=em- 



bryo. 

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



spaces occurring between the larger. The nucellus is compressed, 

 showing remnants of cell walls. The endosperm consists of an 

 outer aleurone layer, the walls with pore canals; this is followed 

 by cells of the same character. The cells of the embryo are 

 smaller. The testa of Veriascwm blattaria in an undeveloped seed 

 consists of the epidermal cells with chlorophyll and the underlying 

 much larger cells also with chlorophyll. 



