FLOWERS OF THE HEATHS AND MOORS 



191 



a thin peaty or humus soil in hollows in lowland 

 areas, so that the lie of the ground must be 

 considered. Except where pools occur, the 

 heath is more or less homogeneous; but where 

 it is wooded, new conditions are introduced, 

 and shade and sun plants both find a foothold 

 in such areas. 



The Habit of Heath Plants. No type of 

 natural vegetation, perhaps, exhibits so marked 

 a habit of growth on a wide scale as ericetal 

 vegetation. 



The most obvious character in open associa- 

 tion, where trees are absent, is the dwarfing 

 of the vegetation. This is due not only to 

 the necessity of a reduction of parts such as 

 leaves, &c., and a certain stem habit, but 

 also to the need for meeting the exposure to 

 the wind. An inland heath in this respect is 

 similar to the vegetation of the sea-coast where 

 wind plays a constant and important part. The 

 type of growth is typically ericoid, as in the 

 heath plants, with whorls of linear, erect leaves, 

 and fastigiate or closely grouped branches, de- 

 veloped much on the lines of the tufted foliage 

 and stems of grasses. Owing to this close habit 

 of the dominant types of heath plants other 

 plants have to adapt themselves accordingly, 

 and even where Ling, &c., is discontinuous, 

 and where there is an alteration of conditions, 

 there are few types except the grass type. But 

 amongst the heath types a few others manage 

 to survive in locally open spots, and these have 

 usually the trailing habit, or else they have 

 the erect rigid habit of St. John's Wort, with 

 few branches and short, not very broad, leaves. 

 Some are rosette plants, as Hawkweeds, 

 Sheep's-bit Scabious. Here and there on rocks 

 or ledges plants having a mat' or cushion habit 

 occur. Many others have a sort of grass habit, 

 as Harebell, Cow-wheat, &c. 



The Height of Heath Plants. There is so 

 little variation in the height of the dominant 

 heath plants that the whole flora might be 

 considered to range between a few inches and 

 2 ft. in height on the average. But in some 

 places the Ling itself is abnormally developed, 

 whilst elsewhere it is equally dwarf and pros- 

 trate. 



The chief factor regulating the height of the 

 heath plants is the wind. The heath formation 

 is open, as a whole, and exposed to strong 

 air-currents, hence, as on the sea-coast, the 

 plants adapt themselves to this in their stunted 

 growth. Furze and Broom first, then Ling 

 and the Heaths may be said to form the next 

 highest type of association. There are plants 

 of intermediate height that struggle upwards 

 amidst the closely branched Ling or Furze, 

 as Heath Bedstraw and Grassy Stitchwort, 

 whilst, as a rule, the Milkwort and the Tor- 



mentil, both grass-heath types also, are trailers 

 that form a third or lowest zone. 



The trees are stunted, and the Birch has on 

 the Birch heath often a more erect habit with 

 reduction of the branches. The Creeping 

 Willow is a dwarfed type also, stunted or 

 bent over owing to the wind. 



The Flowering of Heath Plants. The excep- 

 tionally dry conditions of most heath vegeta- 

 tion have a noticeable effect upon the flowering 

 seasons of the plants. A heath is exposed to 

 intense illumination, a dry atmosphere, and 

 hot sun, with little shade. Hence the thermal 

 constants of the plants that grow on the sandy 

 soil or acid humus of a typical heath are 

 attained more quickly in the main, and the 

 plants are not so backwar.d as those that grow 

 upon hills or in wet places. Here, again, 

 however, altitude plays its part, and when 

 Ling and Heath grow at high altitudes, the 

 plants flower later. 



A considerable number of the plants described 

 in detail in Section IX commence to flower as 

 early as April, as Grassy Stitchwort, Furze 

 (which blooms more or less all the year 

 round), Broom, Heath Bedstraw, Whortle- 

 berry, Meadow Rush, Early Sedge. In May, 

 Milkwort, Red Rattle, Creeping Willow, and 

 Wood Rush are first found in flower. Tor- 

 mentil, Cat's Foot, Common Hawkweed, 

 Harebell, Cross-leaved Heath, Crimson Heath, 

 Cow-wheat, Green-ribbed Sedge, and Heath 

 Hair Grass first bloom in June. Not until 

 July do Pretty St. John's Wort, Sheep's-bit 

 Scabious, Eyebright, Small Bent Grass, of 

 Matweed bloom. Dodder and Pennyroyal 

 linger till August before they open their 

 flowers. 



The Duration of Heath Plants. It is of 

 advantage to plants that are exposed to dry- 

 soil conditions to continue their activities from 

 year to year. By this means, with a rest 

 period in winter, they are enabled with the 

 renewal of their vigour in spring to cope with 

 the more disadvantageous conditions of the 

 summer. The possibility of the germination, 

 growth, and development of an annual is 

 remote, as a rule, upon heath land. It is, of 

 course, necessary that such hemi-parasites as 

 Eyebright and Cow -wheat should come up 

 from seed each year and attach themselves 

 to the Grasses upon which they grow. 



It is also of advantage to the dominant types 

 of heath vegetation that they are shrubs and 

 evergreen in many cases. This enables them 

 to cope the more easily with the conditions, as 

 they have not to renew the shoots each year. 



The Pollination of Heath Plants. Heath 

 vegetation may be either open or closed in 

 character, woodland in the latter case alter- 



