ECOLOGY OF WOODLAND PLANTS. 395 
Fig. 70 is a section of a leaf of the sun-form from a hedgerow. 
The upper epidermis is distinctly cuticularized ; palisade-cells 
much elongated, displaced at intervals by crystal sacs ; spongy 
parenchyma in three layers; air-spaces relatively small. The 
leaf is distinctly thicker and firmer than the shade-form. 
SUMMARY. 
The vegetation of the Huddersfield district is naturally divided 
into three parallel zones :— 
(1) Tox Moss Moor, a part of the Pennines ranging in 
altitude from 1700 to 1000 feet. Of the three zones it is the 
most exposed, the climatic conditions are extreme, the soil 
consists chiefly of deep ill-drained peat, on which Eriophorum 
vaginatum dominates with very few associates. On the higher, 
drier ridges and moor-edges, Vaccinium AMyrtillus with ericaceous 
plants are dominant. Though now practically a treeless region, 
there is much evidence that forests of Betula &c. extended over 
a considerable part of it, and much buried timber is found at the 
base of the peat. At the present time Quercus dies out at 
1200 feet. A characteristic vegetation of Pteris aquilina with 
xerophyte associates covers the hill-slopes and forms a transition 
region to Zone 2. 
(2) Tux Muinrsrone-Grir PraTEAU occupies the central 
portion of the distriet, and the altitude ranges from 1000 to 
500 feet. In contrast to the Moss Moor, it consists of a series 
of fine plateaus with a general dip to the south-east, The rocks 
consist mainly of coarse-grained, jointed sandstones, overlaid by 
shallow pervious soils and in parts by thin, relatively dry peat. 
It is fully exposed to the sun and drying east winds, and 
although the rainfall is moderately high (42 inches), water so 
readily percolates or is drained off that it is a typical, physio- 
logically dry area, and the vegetation is consequently xerophytic ; 
ericaceous plants and xerophytie grasses dominating. Oak is 
the dominant tree, with Birch and Pine. All the trees are 
planted, but often on the sites of primitive forest, and Oak was 
formerly much more abundant than at present in this zone. 
(3) Tue Coan-Mrasure Amnra.—In general the altitude 
ranges from 500 to 200 feet, except to the south-east, where it 
