FLORISTIC REGIONS 99 



small number of 35 species of Astragalus, 2 of Pistacia, 

 and 4 of Clethra. On the other hand, of the genera most 

 represented in Sikkim it has 134 species of Rhododendron, 

 129 of Pedicularis, 77 of Primula, 76 of Corydalis, 66 of 

 Qmrcus, and 58 of Saxifraga. Its most characteristic 

 Order, the Camelliacece, are represented by 71 species, 

 Acer by 42, Vitis by 35, and the Magnoliacece by 33, 

 including a Liriodendron. In its wealth of species and 

 in not a few characters it suggests comparison with the 

 Mediterranean Region. 



NORTHERN ZONE OF HOT SUMMERS. The South 

 Temperate Sub-zone, known, so as to be distinguished 

 from a division of the Southern Zone, as the " Northern 

 Zone of Hot Summers," may be taken to include the 

 islands of the North Atlantic, the Azores, Canaries, and 

 Madeira, the Mediterranean, North African, Levantine, 

 Steppe, and Central Asian Regions in the Old World, and 

 the Prairie and Californian Regions in North America. 

 Its climate is more extreme than that of the sub-zone to 

 the north'of it; and, though there is no real winter, grass 

 is parched in summer. Most of the vegetation is xero- 

 phytic. Needle-leaved Conifer ce; evergreen trees and 

 shrubs, often " sclerophyllous," i.e. with rigid leathery 

 leaves; and, in the driest regions, succulent plants, are 

 characteristic. 



The Azores, Madeira, and the Canaries, all volcanic 

 and rich in endemic species, form three distinct archi- 

 pelagos, although their flora is known collectively as 

 " Atlantic." The Bruyere or Tree-heath (Erica arbor ea 

 L.), species of Laurus, and a wealth of Ferns, are charac- 

 teristic of all of them. With 40 endemic species, out of 

 a total of 478, the Azores are in the main European and 

 Mediterranean. Madeira, with 103 endemic species out 

 of 648, but with its wild plants largely exterminated by 

 cultivation, preserves Tertiary types in Clethra arboreaA.it. 

 and the sapotaceous Sideroxylon, and African connections 

 in Drac&na Draco L. The Canaries, with a larger 

 endemic element (422 species out of 977), are far more 

 African. Their lower ground, where species of Date- 

 palm, Tamarisk, and Euphorbia all bear the specific name 

 canariensis, especially exhibit this relationship. Above 

 this, i.e. from 1600 or 2600 feet up to 4000 feet, is the 

 belt of evergreen Lauracece, Laurus canariensis Webb 

 and Bert., Per sea indica Spreng., and Ocotea fcetens 



