288 OUTLINE OF PLANT GEOGRAPHY 



are bordered by impenetrable mangrove swamps composed al- 

 most exclusively of Rhizophora mangle, the common American 



species. 



As one ascends the stream, the Rhizophora gives way to the 

 •white mangrove/' {Avicennia hitida) which sometimes becomes 

 a large tree with very long aerial roots pendent from the upper 

 branches. Back of the mangrove belt are slightly elevated ridges 

 upon which grow large trees of various kinds. 



Still higher up the rivers, the mangroves disappear completely, 

 and the banks are overgrown with a dense jungle of trees and shrubs 

 corresponding to the gapo of the Amazon. Leguminosae of many 

 species are especially abundant, particularly species of Inga; and 

 the big arum, Montrichardia arborescens, already referred to, forms 

 a close palisade at the outer margin of the jungle. 



Continuing above the tide limit palms become a conspicuous 

 element in the forest, and along the banks, and in the typical 

 riparial forest occur in large numbers and variety, and add a great 

 charm to the river shore. First in abundance and beauty is 

 Euterpe oleracea, whose tall slender stems and feathery crowns 

 occur in thousands. Other characteristic palms are species of 

 Maximiliana and Attalea, with gigantic pinnate leaves, and less 

 striking species of Astrocaryum and Manicaria. Of the smaller 

 palms occurring as undergrowths in the forest, the commonest are 

 many species of Bactris, with slender stems, sometimes hardly an 

 inch thick, and with clusters of showy red or black berries. The 

 climbing species of Desmoncus, already referred to, are very com- 

 mon. Their flexible spiny stems, and graceful feathery leaves, 

 armed with savage hooked spines, are festooned from tree to tree, 

 and remind one of the East Indian rattans. The clusters of scarlet 

 fruits are very conspicuous, and attract attention, as the boat 

 skirts the dense jungle along the shore. 



Next to the palms, perhaps the most striking trees of the riparial 

 forest are the numerous Cecropias, with their big palmate leaves 

 and jointed stems, which occur everywhere along the rivers. 



A bewildering tangle of climbing plants forms a heavy drapery 

 over trees and shrubs, sometimes quite concealing them. These 

 lianas belong to very diverse families, and include morning glories, 

 passion-flowers, trumpet creepers, as well as less familiar genera 

 of Apocynaceae, Melastomaceae, Malpighiaceae and others. 



