160 



MINERAL SALTS ABSORPTION IN PLANTS 



Collecting cell Adjoining cell Pore Excretory cell Cup cell Cuticle 



(b) 

 Fig. 50. The Structure of salt glands 

 a. Salt gland from the leaf of Limonium (Statice) gmelinii (redrawn from 

 Ruhland, 1912); b. Salt gland of Spartina Townsendii (redrawn from Skelding 



and Winterbotham, 1939). 



of sixteen cells with large nuclei, dense cytoplasm and no chloro- 

 plasts or obvious vacuoles. Four large excretory cells are arranged 

 centrally; closely associated with them are four smaller but similar 

 "adjoining cells", and surrounding them are eight flattened cells 

 forming a two-layered cup. The entire gland is enclosed by a rigid 

 cuticle of irregular thickness which is penetrated by a small pore at 

 the tip of each excretory cell. It is through these pores that the salt 

 is excreted. Outside the gland proper, are four collecting cells 

 communicating with the cup cells by protoplasmic connections 

 through pores in the cuticle. The collecting cells serve as a link 

 between the gland and underlying tissues of the leaf, and it is 

 apparently through them that salts are transferred into the gland. 



