146 



HYDATHODES 



with the absence of the characteristic thickenings in the guard- 

 cells ; in surface sections they chiefly differ in their more rounded 

 form (Fig. 72). In some plants but a single water-pore is asso- 

 ciated with each hydathode (e.g. Enchanter's Nightshade, 

 Fuchsia), but in others they are numerous (e.g. Wild Strawberry), 

 and occasionally grouped in shallow depressions that can be 

 recognised with the unaided eye (e.g. Marsh Marigold). 



In a longitudinal section through an entire hydathode of this 



FIG. 72. Water-pores (W.p.) of the Lesser Celandine (Ficaria verna) seen 

 from the surface. St., a normal stoma on the same scale for com- 

 parison. 



type (Fig. 73) the end of the vascular bundle, which is here seen 

 to consist of tracheids only, usually enlarges somewhat, often in 

 a cup-shaped manner. Between the tracheids and the overlying 

 water-pores there is commonly a small-celled tissue, the epithem 

 (ep.), composed of cells with prominent nuclei and dense cyto- 

 plasmic contents ; there is often, however, a space immediately 

 beneath the epidermis. The epithem is traversed by a system 

 of fine intercellular spaces through which the water passes from 

 the tracheids to the water-pores. In many Monocotyledonous 

 water-plants (e.g. Water Plantain, Alisma plantago) the tissue 



