274 BEITISH PLANTS 



partially-drained peat-bogs, dry rocky crags and slopes 

 along mountain valleys, and on heather-moors at high 

 altitudes (1,500 to 2,000 feet). In most cases the pine- 

 woods are artificial, but natural pine-woods occur in the 

 Highlands of Scotland. The tree had a much wider range 

 in former times, for remains have been found in the peat 

 of the Pennines at an altitude of 2,400 feet, although at 

 the present time the upper limit in that district is but 

 1,750 feet. 



The spruce, Douglas-fir, and larch, which are frequently 

 planted, reach higher levels than the pine. In the Pen- 

 nines they occur up to an altitude of 2,015 feet. Above 

 1.800 feet the plants become dwarfed, and at the upper 

 limits the spruce assumes a dense shrubby habit, 2 to 

 3 feet high, and often forming a low mat close to the 

 ground. In Forfar a larch-wood extends up to 2,500 feet. 



The pine produces as much shade as the beech when 

 growing in close canopy, and this dense shade affects the 

 plant itself as well as the undergrowth. The lower 

 branches die away, leaving a long straight stem crowned 

 by a mass of foliage. On the edge of the wood the 

 branches persist right to the ground. Where the shade 

 is most dense only a few mosses occur, and occasionally 

 Monotropa Hypopitys. As in the beech-wood, the ground 

 is covered with a thick layer of slowly decaying leaves, 

 which likewise prevents the undergrowth from developing. 

 In more open parts the chief woody plants are an occa- 

 sional mountain-ash and birch, and invaders from the 

 neighbouring heath e.g., ling, whortleberry, and black- 

 berry. Common herbs are Potenlilla Tormentilla, Galium 

 saxatile, Veronica Chamcedrys, and Oxalis Acetosella. 



A number of plants are found in the primitive woods or 

 ancient plantations in Scotland and North England, and 

 in many cases the relative age of a plantation can be 

 determined by their presence or abundance. These 

 plants include : Linncea borealis, Pyrola minor, P. media, 

 P. rotundifolia, P. secunda, and P. uniflora (winter- 

 greens), Trientalis europcea (chickweed winter -green), 

 Listera cordata (small twayblade), and the colourless 

 saprophyte Corallorhiza innata (coral -root orchid). 



