360 ZONES AND REGIONS [Pt. Ill, Sect. I 



and the rain-forests of the Amazon and its tributaries. It alternates 

 frequently with the savannah, and in this case, as in all dry districts, 

 edaphic influences are in the first place responsible for the change in the 

 character of the vegetation, since savannah prevails on a stiffer soil that is 

 superficially wetted by the rain, whereas woodland occupies a sandy soil 

 that is very permeable to water. The caatingas exhibit thorny bushes, 

 chiefly formed of Mimoseae, among which there rise more or less numerous 

 trees, including the strange ' barrigudos l ' and columnar Cactaceae. Thin 

 lianes climb among the bushes ; epiphytes are absent or are extremely 

 scarce. The herbaceous vegetation is limited to prickly Bromeliaceae 



( Fi g- J 93)- „ u 



The caatingas of Brazil have frequently been described, especially by 



Martins, Saint-Hilaire, Liais, and recently by Detmer. Martins'- gives the 



following vivid account of them : — 



' It is quite different (i.e. compared with the rain-forest) with the forests termed 

 by the Brazilians caatingas, or light-forests, which lose their leaves during the 

 dry season and break out into leaf again only after persistent rain has set in with 

 the wet season. They consist of trees of considerably more stunted growth, and, 

 when leafless, remind the European traveller of the appearance of his native broad- 

 leaved forests at the commencement of winter. They belong chiefly to the northern 

 provinces of Ceara, Rio Grande do Norte, Pernambuco, Piauhy, Goyaz, and Bahia, 

 where they occupy the sandy, primary granite, or Jurassic limestone soils, over 

 immense tracts. Dry districts, poor in springs and whose rivers dry up in summer, 

 hills or plains, are the native country of these remarkable forests. The traveller 

 journeys across them only with fear and trembling during the dry months. Sur- 

 rounding him, as far as he can see, stand the bare leafless stems, motionless, 

 unfanned by the slightest breeze ; not a green leaf, not a juicy fruit, not a verdant 

 blade of grass, on the burning, bare soil ; alone appearing to retain still a fleeting 

 trace of life, are the strangely shapen stems of Cereus, which here like huge 

 candelabra, and there crowded together in serried ranks, stand threatening with 

 their poisonous spines. ... If, however, a sudden shower of rain should loosen the 

 bonds of the vegetable kingdom . . . then, as if by magic, a new world springs into 

 existence. From the richly branched stems, leaves of soft green colour shoot forth, 

 countless rarest forms of flowers expand, the bare limbs of formidable thorny 

 hedges and of climbing plants clothe themselves anew with fresh foliage. . . .' 



As characteristic plants of the caatingas, Martius mentions Spondias tuberosa, 

 Arr., Anona obtusifolia, DC, Caesalpinia pubescens, C. glandulosa, Bert., Cap- 

 paris lineata, Pers., C. longifolia, Gw, C. laevigata, Mart., Pourretia tuberculata, Mart., 

 and Chorisia ventricosa, Nees et Mart., Thryallis brasiliensis, several small species 

 of Bombax, several species of Acacia, of Mimosa, and of Jatropha, ' an angular 

 forked Euphorbia, the single species of this African form that occurs in Brazil' 



The account by Liais does not add any essential points to that of Martius. Yet 

 he mentions the occurrence of many forms of Cactus and a great number of prickly 

 Bromeliaceae, as terrestrial herbs. 



1 With reference to these barrel-trees, see p. 349. 2 Martius, op. cit., pp. 16, 17. 



