CHAP. LXXVI DRY BUSHLAND 291 



sively by monocarpic herbs. The dominant species are Airopsis praecox, 

 A. caryophyllea, Teesdalia nudicaulis, Lotus angustissimus, Erodium 

 Botrys, Galium parisiense, and others. Of perennial herbs only one is 

 common the bracken fern. Not only this but also the monocarpic herbs 

 are dwarfed in growth. The prevailing nanism and the domination of 

 monocarpic herbs are adaptations to the rainless summer and intense 

 atmospheric aridity. 1 



CHAPTER LXXVII. BUSHLAND ON DRY SOIL 



ALLIED to waste herbage is the formation represented by various types 

 of bushland that are more or less xerophytic, and occur in climatically 

 moist districts on dry soil, or have arisen as a consequence of the destruc- 

 tion of forest. Of these, several kinds are denoted in the succeeding 

 paragraphs. 



Hippophaetum is common, for example, in north-west Jutland, 

 grows mostly on sandy soil, and consists of low, spinose, tangled shrubs, 

 which are from half to a metre in height and possess matt leaves that 

 are silvery-grey with scale-like hairs. The dense growth of the association 

 is due to the abundant production of root-suckers. 2 



Similar thorn-bushland occurs in southern Norway on Silurian soil, 

 in Sweden and Central Germany on sunny, stony spots. It usually consists 

 of Prunus spinosa as well as Berberis, Crataegus, Rosa, and Rubus, or 

 mainly of Juniperus communis, or, for instance in Scotland, of Ulex 

 europaeus. Bushland composed of Juniperus is encountered in many 

 other places, for instance, as J. excelsa, in the Transcaspian mountain- 

 flora. 



Garide. In the valley of the Rhone and among the Jura moun- 

 tains there is a similar type of bushland to which the name garide 

 has been applied by Chodat. 3 It is essentially composed of deciduous 

 shrubs, including Prunus Mahaleb, Berberis vulgaris, Ligustrum 

 vulgare, Amelanchier vulgaris, and Crataegus Oxyacantha. On the 

 Jura mountains bushland composed of Buxus sempervirens occurs. 4 

 Baumberger terms this type of bushland in the Jura mountains ' fell- 

 heath '. 



Among other bushlands whose oecology has been so little investi- 

 gated that it is impossible to decide whether they should be regarded as 

 belonging to the formation under discussion, or to steppe or sclerophyl- 

 lous bushland, is : 



Palm -bushland. In Mediterranean countries the dwarf-palm, 

 Chamaerops humilis, may form social communities extending over wide 

 areas and excluding nearly all other vegetation ; its tall rosettes of fan- 

 like leaves seem to spring directly from the ground. 5 Mayr 6 describes 

 palm-bushland that occurs in America and is composed of Serenoa serru- 

 lata : this palm stretches over the ground and clothes sterile sand, on 

 which forest composed of Pinus australis and P. cubensis had formerly 

 grown until destroyed by fire or felling operations. Serenoa has already 

 seized upon many square miles of country. Even when fire attacks it 



1 Vahl, 19046. * See p. 268; Warming, 1907-9. * Chodat, 1902. 



4 Chodat, loc. cit. See Fig. in Borgesen, 1897. * Mayr, 1890. 



U 2 



