274 BRITISH 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 Poteniilla Tormentilla, Galiwm 
saxatile, Veronica Chameedrys, 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 : Linnea borealis, Pyrola minor, P. media, 
P. rotundifolia, P. secunda, and P. uniflora (winter- 
greens), T'rientalis europea (chickweed winter-green), 
Listera cordata (small twayblade), and the colourless 
saprophyte Corallorhiza innata (coral-root orchid). 
