146 



HYDATHODES 



with the absence of the characteristic thickenings in the guard- 

 cehs ; 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 arc 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 {IV. p.) of the Lesser Celandine (Ficaria verna) seen 

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

 parison. 



type (Fig. j^) 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 commonl)' a small-celled tissue, the cpithem 

 {ep), composed of cells with prominent nuclei and dense c^'to- 

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

 beneath the epidermis. The epithem is tra\-ersed bj' a system 

 of fine intercellular spaces through which the water passes from 

 the tracheids to the water-pores. In many Monocotylcdonous 

 water-plants {e.g. Water Plantain, Alisina plantago) the tissue 



