270 Eduard Riibel 



root stems. Only few species can endure the strenuous habitat 

 condition. Two associations are well known. The American 

 Mangrove consists only of Rhizophora fnangle, Laguncularia 

 racemosa, Avicennia tomentosa, and A. nitida. The association 

 grows on the tropic mud beaches and covers the shores as far 

 north as southern Florida. The eastern Mangrove, Rhizophore- 

 tum mucronatae, is much richer in species. It has its center in 

 the Malay Archipelago. Impoverished association specimens are 

 found as far distant as southern Japan and New Zealand. 



J. Laurisilvae: Laurel-leaved forests. — In Laurisilvae the domi- 

 nant trees, if dicotyledons, have evergreen leaves which are 

 usually glabrous, bright green, and at right angles to the incident 

 light, relatively large intercellular air spaces often being pres- 

 ent and the buds protected; if gymnosperms dominate, these 

 bear broad evergreen leaves or scale-formed ones covering the 

 twigs tile-fashion. These forests continue from the rain forests 

 poleward and upward where the rain forests can no longer 

 thrive on account of diminishing average temperature and in- 

 creasing temperature variations, but like them they are corre- 

 lated with regular rainfall, relatively high humidity, and uni- 

 form temperature — in all, a temperate oceanic climate. These 

 forests are distributed in Pacific North America, Florida, Chile, 

 Patagonia, the Canary Islands (beautiful laurel forest), Madeira, 

 Portugal, Cape Province (Knysna), the Himalayas, Japan, New 

 Zealand. The misty forests of middle and northern Florida and 

 Chilean Valdivia are of this kind. They are mosdy dominated 

 by evergreen beeches, as, for example, Nothofagus betuloides. 

 The climate has a mean temperature of only five to nine degrees 

 Centigrade, but only nine degrees difference between winter 

 and summer, with a great deal of precipitation all the year 

 round. 



