328 MESOPHYTES sect, xvi 



CHAPTER XCI. MESOPHYTIC BUSHLAND 



In discussing certain bushlands occurring far north and on high 

 mountains, it was pointed out ^ that perhaps these would most, correctly 

 be regarded as mesophytic, although they display strongly developed 

 means of checking transpiration. 



In Greenland and other arctic places such bushland presents itself in 

 the form of willow-bushland sahcetum.^ One finds it at the bottoms 

 of valleys and in ravines, in sheltered sunny spots, particularly where 

 flowing water or water trickling from rocks provides a uniform supply of 

 moisture, and where humus accumulates and earthworms burrow. In the 

 south of Greenland it is Salix glauca that gives rise to extensive, frequently 

 almost impenetrable bushland, which is some metres in height, but farther 

 north attains scarcely one metre and produces more or less prostrate 

 branches. Beneath the willows there flourish large and broad-leaved, 

 fresh-green, perennial herbs, such as Archangelica officinalis, Oxyria, 

 Taraxacum officinale, Alchemilla vulgaris, species of Potentilla, Epilobium 

 angustifolium, and Arabis alpina, also Poa alpina and other broad-leaved 

 grass-like plants, ferns, and large lax mosses, including Hylocomium, 

 Hypnum, and Dicranum. Here and there leaf-peat is formed.^ 



On Norwegian mountains there appears a willow-region, which differs 

 from that in Greenland in that the bushland is formed by many different 

 species of SaHx, including S. Lapponum, S. lanata, S. Arbuscula, S. glauca, 

 S. phyhcifolia, and S. nigricans, also in that the ground entertains a still 

 richer herbaceous flora. This bushland provides a transition to oxylophytic 

 bushland. Bonnier and Flahault ^ apply to it the term of ' willow-prairie ', 

 and point to these extensive willow-bushlands as providing a distinction 

 from the Alps, where most of the same species of Salix occur but do not 

 dominate to the same extent. Bushland of the same type occurs in 

 Lapland and Siberia. Willow-bushland is very general throughout 

 temperate Europe on the banks of streams outside the marshy belt, and 

 is represented, for instance, in Servia by Adamovicz's ' willow-meadow ' ^ ; 

 it even occurs on flat islets in the Amazon.^ Other bushlands above the 

 limit of forest are composed of birches or birches and willows, which are 

 accompanied by alders, other shrubs, and such tall perennial herbs as 

 Aconitum, Ranunculus, Digitalis, Geranium sylvaticum, Vicia, and 

 Lathyrus, or, in the interior of Lapland, by Veratrum, Senecio nemorensis, 

 and others. Birch-bushland here and there merges with birch-forest. 



Among mesophytic bushlands that of green alder may be mentioned. 

 Alnus viridis, in the Alps at altitudes of 1,200 to 2,000 metres, on naturally 

 irrigated spots, gives rise to dense bushland with tall perennial herbs 

 clothing the ground.' 



The lowlands of temperate regions abound in bushlands similar to 

 those formed by willows. Evergreen holly-bushland appears on the south- 

 west coasts of Norway. 



Mesophytic and xerophytic bushlands merge with one another. As 



* p. 215. ^ Warming, 1887 ; Pohle, 1903. * Pohle, loc. cit. 



* Bonnier et Flahault, 1879. ' Adamovicz, 1898. 



* Grisebach, 1880, p. 388. 

 ' C. Schroter, 1904-8 ; Brockmann-Jerosch, 1907, p. 275. 



