Chap. VI] KDAPHIC INFLUENCES IN THE TROPICS 409 



lion, and consequcntl}- tlic transpiration, is much more considerable 

 and more regular in liumid sea-districts than in those with sh'ght rain- 

 fall. Ucnsc and tVequently repeated cloitdiiicss apparently nprcscnts the 

 most essential climatic condition for tlie occurrence of mangrove in the 

 tropics. 



Bej-ond the tropics the limits of the formation as a whole, and those 

 of its individual members, are chiefly determined by temperature : — 



The North-East limit of the Eastern Mangrove as a closed formation, 

 according to \\'arburg's observations, apparently lies in South Liu-kiu 



Fig. 230. Mangrove in Floiid.i. Interior view. Rliizophora Mangle. From ' UanJen .ind torcst.' 



(Iriomotte, 25° N.) ; Warburg has not seen tall mangrove further North. 

 Even there it is ahead}- impoverished and consists of only four species (Bru- 

 guiera gymnorrhiza. Rliizophora mucronata, Sonneratia acida, ? Avicennia 

 officinalis) ; in the form of isolated individuals. Rhizophora mucronata still 

 appears in South Japan (Kagoshima, 32" N.) as the most northerly repre- 

 sentative of the Eastern Mangrove flora. In a South-East direction the 

 mangrove continues to the tropic of Capricorn in undiminished luxuriance, 

 but becomes lower in stature and poorer in species on the coast of New South 

 Wales (Avicennia officinalis, Aegiceras). Bushes of Avicennia occur even 

 in New Zealand and as far as Chatham Island (,44° S.). The North- West 

 limit of the mixed mangrove lies at the mouth of the Indus ; beyond this 



