Chap. VI] EDAPHIC INFLUENCES IN THE TROPICS 395 



almond-like fruit of Terminalia Catappa, under the thick juicy mesocarp of 

 Scaevola Koenigii, in the testa of Cycas circinalis and of Calophyllum 

 Inophyllum. Heritiera littoralis possesses boat-shaped, carinate, hard- 

 shelled nuts, which, thanks to a large internal cavity, are among the best 

 floaters ; and the individual fruits of the huge infructescence of Pandanus, 

 in spite of their beautiful red colour, apparently acquired to attract animals, 

 are hard and almost free from sap, and are chiefly disseminated by marine 

 currents, as is shown by their frequency in drift cast on the shore. 



The capacity for floating possessed by the seeds of most plants of 

 littoral woodland, and shared by the partly identical species of the open 

 formations, has occasioned the extremely wide distribution of the plants 

 of these groups of formations. Species from the mangroves, which will be 

 described hereafter, are also provided with floating fruits or floating seeds. 

 But such floating fruits and seeds appear in no formation in such perfection 

 and variety as in littoral woodland above high-tide level. 



iv. WOODLAND FORMATIONS BELOW HIGH-TIDE MARK. 



Within the tropics, as in higher latitudes, the belt of shore within reach 

 of the tide — ' the beach ' — is quite devoid of vegetation on sandy or clayey 

 coasts exposed to the wind and breakers, and bears only Algae on rocky 

 coasts ; on the other hand, in creeks and lagoons, where the movements of 

 the sea and air are weaker, it is covered by woodland that is sometimes 

 more shrub-like or bush-like, sometimes forest-like, and is termed mangrove 

 or tidal woodland. It differs from all inland-formations as regards both 

 its flora and its oecology. 



Like the littoral woodland above high tide, mangrove consists mainly of 

 species that are very widely distributed. Nevertheless, two extensive areas 

 may be sharply distinguished from one another — an eastern, which extends 

 from East Africa over Asia into Australia and Polynesia, and a western, 

 which embraces the West African and American coasts. 



The Eastern Mangrove. 



The eastern mangrove, which shows its greatest wealth of forms in 

 Further India and in the Malay Archipelago and may have originated 

 there, consists, with the exception of a few rare species that doubtfully 

 belong to mangrove, of the following forms : — 



RJiizoplioraceae: Rhizophora mucronata, Lamk., R. conjugata, Linn., 

 Ceriops Candolleana, Arn., C. Roxburghiana, Arn., Kandelia Rheedii, W\ 

 et A., Bruguiera gymnorrhiza, Lamk., B. eriopetala, W. et A., B. caryo- 

 phvlloides, Bl., B. parviflora, W. et A. Combretaceac: Lumnitzera 

 racemosa, Willd., L. coccinea, W. et A. LytJiraceae : Sonneratia apetala, 



