ii ericace^ 259 



Andromeda 



A. polifolia is a small glabrous bog plant, seldom 

 above 6 inches high. The leaves are evergreen, glaucous 

 below, and with their edges rolled up — a provision 

 found in many plants growing in peat bogs in cold 

 climates. The air is often saturated with moisture for 

 weeks, and the summers are short. If the stomata or 

 breathing pores, which are on the under side of the 

 leaves, were liable to be clogged with moisture, it might 

 often happen that, even when the sun appeared, it would 

 take so long to free the passages that dew and rain 

 might come on again before they were open. Under 

 these circumstances it is of great importance to protect 

 the stomata, and one way in which this is effected is by 

 rolling the leaves. We find this arrangement in some 

 of the Silenes, Heaths (see p. 27), in Azalea, Cranberry 

 ( Vaccinium Oxycoccos), Crowberry (Empetrum) (see 

 Fig. 11, p. 28), Ledum, some Willows, and some of the 

 grasses associated with them. Certain grasses have the 

 leaves flat in fine weather, but are able to roll them 

 up if it is wet. 



LoiSELEURiA (Azalea) 



L. procumbens is a low trailing moorland shrub, found 

 in the Scotch mountains, with evergreen leaves rolled 

 back at the edges. The small rose-coloured flowers are 

 borne in terminal clusters. The anthers open inwards 

 and surround the pistil, so that insects dust themselves 

 on one side with pollen, and touch the stigma with 

 the other. Gradually, however, they bend over towards 

 and fertilise the stigma. 



Vaccinium 



Honey is secreted by a ridge on the ovary. The 

 anthers have lateral appendages. AVe have four species. 

 Two are deciduous, with black or bluish berries ; of these 

 V. Myrtillus has toothed, V. uliginosum entire leaves. 

 The other two are evergreen, with red berries ; one, V. 



