426 ZONES AND REGIONS [Pt. Ill, Sect. II 



mesothermic, and are in particular richly represented by Cruciferae in 

 both temperate zones. The Papaveraceae and Fumariaceae are almost 

 exclusively north temperate ; the Capparidaceae are confined to the dry 

 districts of the warm belts ; and the few Resedaceae are mainly 

 Mediterranean. 



Of the family Cistiflorae, the Cistaceae are mesothermic and chiefly 

 inhabit Mediterranean countries, the Violaceae occur in both temperate 

 zones, the mainly tropical Ternstroemiaceae reach their northern limit 

 in China and Japan (Camellia), the Tamaricaceae chiefly inhabit Medi- 

 terranean countries and Central Asiatic deserts. 



The almost wholly American Cactaceae, which alone compose the 

 Opuntinac, are abundantly represented not only within the tropics, but 

 also in the warm temperate belts, and are of extreme physiognomic 

 importance in the desert flora, particularly of North America. 



The temperate Cohimnifcrae belong chiefly to the Malvaceae, which 

 occur in the form of shrubs and herbs both in the north and in the south. 

 The chief large extra-tropical genus of Tiliaceae is Tilia ; its species are 

 forest trees of the north temperate zone. The pre-eminently tropical 

 Sterculiaceae are represented in temperate Australia by the Lasiopetaleae. 



The GruinaleS) although the majority of them are mesothermic, are 

 only of subordinate importance in the composition of the vegetation of 

 the globe, if we except the Geraniaceae, which possess numerous species 

 in both hemispheres, but especially in South Africa (Pelargonium). The 

 other temperate Gruinales belong to Linaceae, Oxalidaceae, Balsaminaceae, 

 and Tremandraceae, which last are confined to Australia. 



The Terebintkinae, with few exceptions, require heat, and in their 

 mesothermic forms therefore are confined to the belts with mild winters, 

 where most of them in large numbers inhabit dry districts. The Zygo- 

 phyllaceae are mainly halophytes of desert districts in both hemispheres ; 

 the Rutaceae, particularly as shrubs, form the principal constituents of 

 xerophilous woodlands, specially in South Africa and Australia. The 

 mainly tropical Anacardiaceae play a part similar to that of the Rutaceae, 

 but they are specially important in the Mediterranean flora (Pistacia, 

 Rhus — the latter genus is also North American and East Asiatic). 



The Aesculinae are represented by tree-species of Acer in the north 

 temperate forests, specially those of North America, China, and Japan. 

 The Hippocastanaceae are likewise mainly North American; Aesculus 

 Hippocastanum is, however, distributed from Greece to North India. Only 

 a few Sapindaceae occur. 



The Fraugulinae contribute numerous species, particularly to the shrubby 

 vegetation of both temperate zones, for instance chiefly in America 

 species of Ilex (Aquifoliaceae), also several Celastraceae such as species 

 of Euonymus in the northern zone, species of Gymnosporia in South 



