THE STRUCTURE OF PLANTS. 9 



the pulp of fruits, etc., are termed parenchyma or cellular 



tissue. 



B 



Diagram C shows prosenchyma or woody tissue — 1, 

 woody fibres ; 2, same showing interior. 



Prosenchyma consists of woody fibres (lignine) closely 

 packed. It is formed by the gradual thickening of the 

 cell-walls, and close union of several into bundles, which 

 are of various lengths, overlapping each other, but always 

 terminating at both ends in a point. These long thick- 

 walled cells are in fact the woody substance of the plant. 

 The inner bark (liber or bast), the nerves and veins of 



