564 WEED FLORA OF IOWA 



Wild Morning Glory {Convolvulus sepium L.). 



The testa of the seed of the common morning glory consists of 

 an outer layer of elongated cells containing the blackish pigment 

 followed by the Malpighian cells with small cell cavity and promi- 

 nent light line. The colorless parenchyma cells are thick-walled 

 followed by a compressed indistinct layer, the compressed nucellus 

 and the endosperm cells. 



Cultivated Morning Glory (Ipomoea purpurea (L.) Roth.). 



The black-brownish seeds are rough. The testa consists of a 

 superficial layer of cells with granular brownish contents. The 

 Malpighian cells m occur underneath ; the light line is near the 

 upper part of the cell, cell cavity small. The cells of the paren- 

 chyma layer are compressed. The cells of the endosperm are thick- 

 walled and somewhat mucilaginous. 



Dodder (Cuscuta epithymum Murr.). 



The small seeds are minutely roughened and velvety. The outer 

 layer of the testa consists "of large cells with yellowish contents, 

 the following layer consists of thick-walled cubical or prismatic 

 cells p, the colorless Malpighian cells m follow. They are elongated 

 with a small cell cavity. The layer following consists of com- 

 pressed cells, tangentially elongated. The endosperm layer con- 

 sists of an outer aleurone layer of nearly square cells. The cells 

 below are irregular. The endosperm cells contain compound or 

 simple starch grains and protein. 



BORAGINACEAE, BORAGE FAMILY. 



Wild Comfrey (Cynoglossum virginianum L.). 



The rough fruits are covered with hooked appendages, the sides 

 roughened with small colorless points; the epidermal layer is ir- 

 regular and prominent, in some cells developed into short trichomes, 

 whose walls are greatly thickened. The epidermal walls and con- 

 tents are blackish, the underlying sclerotic parenchyma cells have 

 thick walls and are blackish. The parenchyma cells of the testa 

 are thinner walled and colorless, followed by the compressed layer 

 of the nucellus n. The endosperm cells are longer than broad, 

 colorless, contain protein and fat. 



