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



seiited in the first place by the Passifloraceae, Begoniaceae, and Flacour- 

 tiaceae, also by the Loasaceae (America), Samydaceae, Turncraceae, 

 Caricaceae, some of the species of which are common and prominent. 



The ]\Iyrtijiorac consist exclusively of megathermic species in the 

 Melastomaceae, Combretaceae, and Rhizophoraceae, of which those of the 

 first family play a prominent part, especially in America, as fine blossoming 

 shrubs and herbs, whilst to the last two the majority of shrubs and trees 

 of the mangroves ^ belong. Neither the Oenotheraceae nor the Lythraceae 

 are absent. 



Of the Rosiflorac, the Chrysobalaneae are exclusiveh- megathermic, 

 whilst the other groups of Rosaceae consist almost exclusively of meso- 

 thermic plants and therefore within the tropics occur only on mountains. 



The three families of the Lcginiiinosac, the Mimosaceae, Caesalpiniaceae 

 and Papilionaceae, belong to the most important groups of forms of the 

 tropical flora. They include trees, shrubs, and herbs, that frequentl)' climb 

 and are equally important in humid and dry districts, in woodland andi 

 in grassland ; man}' are remarkable for their fine flowers. 



The different families grouped together tentatively as Hystcrophyta are 

 pre-eminently megathermic, and include many of the most unique products 

 of the tropical flora, especially among the Aristolochiaceae, Rafflesiaceae 

 and Balanophoraceae. 



The Eiicinac arc with few exceptions mcsothermic, and therefore quite 

 unimportant in the true tropical flora. They however show numerou: 

 species in the mountain flora — Vaccineae, Rhododendron. 



Among the PritiinliiiacWxe Myrsinaceae are exclusively tropical, wherea- 

 the Plumbaginaceae include only a small number of megathermic species 

 and the few Primulaceae are alpine plants. 



The families of the Diospyrinae — Ebenaceae, Diospyraceae, Sapotaceae— 

 consist almost exclusively of tropical woody plants. Several of thi 

 Sapotaceae are commonly cultivated. 



Among the Contortae, the Loganiaceae, Apocynaceae. and Asclc 

 piadaceae are represented in many species of the most diverse forms c 

 growth, whilst the Oleaceae and Gentianaceae, as mesothermic families 

 occur only as mountain plants. 



The Tnbiflorac possess many megathermic species among the Convol, 

 vulaceae, and in the Boraginaceae the tribe of the Cordieae, characterizeij 

 by stone-fruits, is purely tropical. 



The most important tropical family of the Pcrsonatac is that of Solanaceai 

 to which very numerous herbs and shrubs aiid some small trees belons 

 The pre-eminently megathermic families Bignoniaceae, Gesneraceae. an 

 Acanthaceae have numerous representatives, and the Lcntibulariacea 



' See Chap. \'I of this section. 



