AMOUNT OF LITTER PRODUCED. 773 



is generally beneficial for forest plants, which can overpower 

 this w r eed only when they have formed a closer canopy of 

 shade. [In Britain, however, the heather serves often as a 

 protection to young plants against spring-frosts, and they do 

 not suffer from its presence so much as in the drier climate of 

 the Continent. Tr.J 



The broom (Cytisus scoparius) is produced by nearly every 

 kind of soil ; it is chiefly prevalent on silicious soils, but also 

 grows on argillaceous schist, quartzite, limestone, and even on 

 chalk. It always implies an admixture of certain clay in the 

 soil. It resembles heather in requiring a complete exposure 

 to light and a moderately warm atmosphere. 



Among ferns, the widely-spread bracken (Pteris aquilina) 

 is most important, Aspidium I^iJi-r-uias and Asplenium F'dir- 

 fii'iniiHi also are used as litter. They require a moist, or even 

 wet soil, but cannot stand stagnant moisture. Half-shaded 

 localities, or fully exposed but cool, damp places, suit them 

 best. 



They grow best in moist, no longer completely closed old 

 woodlands, especially in spruce and silver-fir forests, with a 

 moderate soil-covering of moss. Clearings for plantations, on 

 northerly aspects with a rich soil, also produce a vigorous 

 growth of ferns. 



Bilberry (Vactin iinn Myrtillns) and other species of Van-i- 

 uinm are less frequently used as litter than the above- 

 mentioned plants ; their stems are usually too woody and no 

 weeds decompose more slowly. They require an amount of 

 clay in the soil, and needs shade in soils free from clay, and 

 consequently dry. 



Species of V actinium hence are found in loamy soil in 

 lightly shaded, old woods, when the soil has become super- 

 ficially impoverished ; more on warm than on cold aspects, 

 both in broadleaved and coniferous forests. A large supply 

 of Vacciniitni litter, therefore, always implies deteriorating 

 old woods, or stunted young woods containing blanks. On 

 superior soils a vigorous growth of bilberry is also found in 

 young woods not yet fully closed. The bilberry, like many 

 other forest weeds, has a superficial root-system, but no other 

 weed covers the ground so thoroughly with its densely matted 



