MICROSCOPIC STRUCTURE OF WEED SEEDS 



529 



Fig. 406. Black Bindweed. Transverse section of the fruit. C, calyx consist- 

 ing of the outer epidermis aep, the mesophyll m and the inner epidermis 

 iep ; F, pericarp consisting of the epicarp ei with cuticular warts w, the 

 mesocarp p and the endocarp end ; S, testa consisting of the outer 

 epidermis ae, the cross-cells q and the inner epidermis ie ; E, endosperm 

 consisting of the aleurone-cells al and the starch-cells s. X 160. 

 (After Winton, Conn. Agr. Exp. Sta.) 



in the ripe fruit. Six primary, sparingly branched vascular 

 bundles pass longitudinally through the ground tissue of the 

 mesocarp, one in each angle and one in each of the faces. 

 4. Endocarp (end). Like the inner mesocarp, the cells are usu- 

 ally obliterated in the mature seed and are seldom evident either 

 in cross section or in surface view. 



Testa (S). — Three coats, analogous to those of buckwheat, but 

 differing in form, make up the testa. 1. Epidermis (ae). As in 

 buckwheat, the epidermal cells are wavy in outline; but in bind- 

 weed they are strongly elongated, whereas in buckwheat they are 

 nearly isodiametric. 2. Cross-Cells (q). Most of the cells of 

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