568 



WEED FLORA OF IOWA 



SOLANACEAE, NIGHTSHADE FAMILY. 



Horse Nettle (Solarium carolinense L.). 



The testa consists of an outer row of cells whose walls are 

 mucilaginous; the underlying cells are thick-walled with interven- 

 ing air spaces broad below and narrow above. The cells of this 

 layer contain the yellow pigment. The underlying parenchyma 

 layer is compressed, composed of colorless cells which are longer 

 than wide; the layer adjacent to the endosperm is compressed 

 and not clearly defined. The cells of the inner portion of the 

 endosperm are smaller and contain protein. Cells of embryo are 

 small and contain protein. 



Fig. 434. Microscopic structure of the seeds of some Solanaceous weeds. 



I. Jimson Weed (.Datura stramonium). II. Blank Nightshade (Solatium ni- 

 grum). III. Buffalo Bur (Solanum rostratum). IV. Horse Nettle (Sola- 

 rium carolinense). V. Ground Cherry (Physalis pubescens)- 



ep=epidermis. en=endosperm. pal=palisade cells. em=embryo. p=parenchyma. p 1 = 

 elongated parenchyma cells. 



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



