137 



Mammoth ceiba (Criha pcntaudra (L.) Gaertn.) and guana- 

 caste (Entcroluhiiiiit cyclocarpit))! (Jacq.) Griseb.) trees are still 

 to be found but many have been destroyed to establish plantations 

 or for timber. However, most of the trees, especially on the 

 bench, are small to medium size, forming a low-topped forest. 



The river is bordered with a fringe of trees and a dense thicket 

 of shrubs, lianas, etc. Along the river and on the sand and gravel 

 bars one finds a variety of woody and herbaceous species mostly 

 of wide distribution and often of a weedy nature, e.g.. Cenchrus 

 cchinatus L. ; Mimosa pigra L. ; Polygonum pcrsicarioides HBK. ; 

 Solanum nudum HBK. ; Tridax prociimhens L. ; Jussiaca repens 

 L. ; Crotalaria retusa L. ; Prophylhim punctatum (Mill.) Blake; 

 Commclina elcgans HBK. ; Cyperus roiundus L. ; Trichachne insu- 

 lar is (L.) Nees ; Scoparia dulcis L. ; Borreria laevis (Lam.) 

 Griseb. ; Polypremum procnmbcns L. ; Oxalis Neaei DC. ; Lobelia 

 splendcns Willd. ; Pistia Stratiotes L. ; Cissus sicyoides L. ; Portu- 

 laca pilosa L. ; Portulaca oleracea L. ; Croton lohatus L. ; Cassia 

 occidentalis L. ; Mimosa pudica L. ; Miintingia Calabura L. ; Tali- 

 num triangularc (Jacq.) Willd.; Lippia nodiflora (L.) Michx. ; 

 Lippia rcpcns HBK.; Lantana Camara L. ; Priva lappulacea (L.) 

 Pers.. etc. 



A much more interesting area for the botanist, however, is the 

 bench where the most arid conditions seem to prevail and which 

 is largely forested. In some places the growth is moderately open 

 and one can move about easily but much of it is dense and entan- 

 gled with numerous lianas which, together with the fact that 

 many of the species are armed, make it necessary to do consider- 

 able cutting with a machete in order to penetrate any distance. 

 Herbaceous species appear to be scarce in the forest of this region, 

 at least in the dry season when even the leaves of the woody plants 

 curl and whither and the soil, which is light colored, becomes dry 

 and powdery. Many of the trees have an ash-colored bark w^hich 

 imparts a somewhat ghostly efifect to the landscape. An outstand- 

 ing feature of the vegetation is the occurrence of two species of tree- 

 like cacti often 20 or more feet in height. One is an undescribed 

 species of Ccreus and the other an undescribed Opunfia. Several 

 other cacti sj>ecies both terrestrial and ejMphytic also occur here. 

 Another notable feature of this forest is the extremely large 

 number of parasitic mistletoes {Phoradciidron and Struthanthus 



