332 MESOPHYTES SECT, xvi 



The soil varies widely in nature, and the vegetation on the ground 

 varies accordingly ; the most important varieties are : (a) soil with mild 

 humus ; (6) soil with sour humus. 1 As a whole, the beech prefers a good, 

 deep, marly soil. 



(a) The mild humus-soil of beech-forest is friable, porous, and, being 

 excavated by earthworms as well as other small animals, it is well venti- 

 lated. The volume of its pores in the superficial layers is 50-60 per cent. ; 

 its particles are freely mobile. In the height of summer the ground is 

 often almost covered with brown, faded beech-leaves, which, together 

 with fallen twigs, cupules, and so forth, form a thick carpet that is sharply 

 cut off from the disintegrated substratum. Only here and there, where 

 light penetrates, does one find Spermophyta, including Asperula odorata, 

 Oxalis Acetosella, Anemone nemorosa, A. ranunculoides, Hepatica, Viola 

 sylvatica, Mercurialis perennis, Melica uniflora, Milium effusum, Stellaria 

 nemorum, species of Corydalis, and Hedera Helix. Mosses are wellnigh 

 unrepresented where the thick layer of dead leaves lying on the floor 

 of the forest checks them ; those that do sometimes occur, for example 

 Bryum argenteum, form a very thin coating over the soil. 



The vegetation on the ground of beech-forest has the characteristic 

 that it is a spring-vegetation with a very brief vegetative season. It must 

 utilize the light before the high-forest is foliaged, or while this shows only 

 young leaves. The acts of flowering, assimilation, and fruiting, follow in 

 rapid succession, so that at midsummer a number of species are only 

 represented above ground by slight traces. Such is the behaviour of the 

 plants that are particularly characteristic of beech-forest in northern 

 Europe namely, of such plants as species of Anemone, Corydalis, Gagea, 

 and some species of Primula. 



But there are other plants that remain green for a longer period : 

 among such are Mercurialis perennis, Oxalis Acetosella, Stellaria Holostea, 

 S. nemorum, Pulmonaria officinalis, Luzula pilosa, Carex digitata, C. re- 

 mota, and the grasses Milium effusum, Melica uniflora, Dactylis glomerata, 

 Poa nemoralis, and others. 



In some of the early-flowering species the embryo has reached only 

 a very early stage of its development when the seed falls, as in Eranthis 

 hyemalis, and it may even be unicellular, as in Ficaria and Corydalis cava. 

 This may possibly be correlated with the fact that these spring-plants 

 enjoy only a short vegetative season ; the seed acquires nutriment from 

 the parent plant, but the subsequent development that is normally con- 

 tinued on the parent plant does not take place until the detached seed 

 experiences a secondary process of ripening. 



In accordance with the brevity of the vegetative season and with the 

 early date of flowering, nearly all the species are perennial herbs ; yet 

 such annuals as Impatiens Noli-me-tangere and Cardamine impatiens are 

 not wanting. 



The loose texture of the soil favours the development of horizontal 

 subterranean travelling shoots. These are possessed by numerous species, 

 including Aspidium Dryopteris, Anemone nemorosa, A. ranunculoides, 

 Asperula odorata, Mercurialis perennis, Dentaria bulbifera, Stellaria 

 nemorum, S. Holostea, Oxalis Acetosella, Adoxa Moschatellina, Stachys 



1 Consult P. E. Miiller, 1878, 1884, 1887 a, 1894; Hock, 1895. 



