TISSUES FOR SYNTHESIS 141 



leucoplasts. This reserve starch is stored in the 

 parenchyma of well-protected parts of the plant. 

 Inulin is similarly stored in the parenchyma of tubers 

 and roots. Alkaloids and calcium oxalate crystals 

 may also be stored in the parenchyma cells, while 

 tannins are frequently found in bark parenchyma 

 cells. 



Secretion Cavities. — The volatile oils or other 

 products of secretory cells are usually stored in cavities 

 of lysigenous or schizogenous types or may be con- 

 tained in the gland cells. 



Collenchyma Cell Walls. — The walls of many cells, 

 especially those of seeds and fruits, are thickened by 

 deposition of cellulose. This cellulose may be classed 

 as a reserve nutrient and may possibly be converted 

 into assimilable form if required. Collenchyma is 

 is thus a tissue of synthesis, a supporting tissue and 

 a storage tissue. 



Cavities of Stone Cells and Fibers. — Storage of 

 nutrient material within the cavities of stone cells 

 and fibers occurs in comparatively few instances. 

 Materials stored in these thick-walled cells are not 

 as readily available for use as nutrients as are those 

 contained in the thinner-walled parenchyma. 



