Heather 



Erica tetralix may at once be recognized by the paler 

 colour of its flowers. Unlike Erica cinerea, it is fond of 

 boggy ground, being rarely found on the dry hillsides, Jind 

 the plants do not grow in such close proximity nor so densely 

 as those of the other two species. E. tetralix continues to 

 send out flower shoots throughout the summer, whereas the 

 bell heather and ling do so only exceptionally. This latter 

 species, besides being the most common, is also found at 

 the greatest elevations. On the Cairngorms the limit of the 

 growth of ling is about 3,300 feet, but it is not often seen 

 above the 3,000 line. During the last 500 feet of its vertical 

 range, the plants show a creeping or prostrate habit, and 

 rarely, if ever, produce any flowers. I have frequently come 

 across clumps of white heather — easily recognizable by their 

 lighter tinge of green — at very high levels. 



The ling seems to be one of the slowest recoverers from 

 the effects of winter snow amongst all high-growing plants. 

 Snow drifted into a corrie by heavy winter gales may lie 

 till late in the spring or well into summer, and the ling, when 

 first exposed, is found to be pressed flat on the ground. If 

 conditions are favourable, the plants gradually assume the 

 upright pyosition once more, but should the weight of snow 

 have been unusually great, or the melting more protracted 

 than usual, the heather plants remain prostrate, or partially 

 so, throughout the season, though they endeavour to shoot 

 in that position as far as the short period of warm weather 

 remaining permits them. Heather is rarely killed by 

 drought, being an essentially zerophytic plant. Its small 

 leaves are tightly rolled back at all times, protecting the 

 stomata or breathing pores from hot sunshine or strong dry- 

 ing winds, and thus preventing too rapid transpiration. 



But the remarkable drought which characterized the sum- 

 mer of 1919 was sufficient to kill outright large stretches of 

 both Calluna vulgaris and Erica cinerea, the plants turning a 

 light grey colour and becoming absolutely dead. In other 

 cases the flower buds failed to open and either remained 



141 



