06 



Wallenia laiirifolia Psychotria sp. 



Asclepias nivea Chiococca parvifolia 



Solamini triste Diapedmni assiirgens 



Havielia liitea Lobelia sp. 



Psychotria lasioplitlialma Adenostenivm Berterii 



But no mere list can give one the least idea of the vegetal 

 wealth and beauty of one of these gorges, -and they are all the 

 more striking in contrast with the arid slopes through which they 

 have cut their way. With vines festooned among the trees and 

 shrubs and almost all the trees covered with epiphytes the scene 

 is most beautiful. 



These gorges are a fine example of the action of an edaphic 

 factor as a determinant in the plant-covering of a restricted area. 

 The climatic and primary soil conditions are practically identical 

 in the cafions and the slopes. But the water that is at the bottom 

 of all these gorges is almost the sole factor in producing such 

 profusion on the one hand, and the lack of water is certainly 

 the chief cause of such scarcity on the other. The moisture and 

 consequent decomposition of successive generations of herbaceous 

 plants make a rich, damp compost, and we therefore find here a 

 profusion of plants in striking contrast to the poverty of the ridges 

 and slopes. 



River Bottoms and Deltas 



The sterility of most of the river bottoms, particularly where 

 they spread out to form the delta, is a very marked feature of this 

 region.* With the exception of species of Phnniera and a few 

 other tree species, these areas are without arboreal vegetation. 

 A rather rank growth of somewhat xerophytic shrubs and 

 weeds gives the whole river bottom a characteristic appearance 

 not unlike a typical "scrub" of the Bahamas. The line of 

 demarcation between these sterile areas and the well-wooded hills 

 that rise abruptly on both sides is very sharp ; and it is quite as 

 much the sudden change as the sterility that will strike the col- 

 lector. This sterility is caused by the floods that annually wash 



* Taylor, N. Botanical Notes on the Vegetation of the High Maestra. Forestry 

 Quarterly 4 : 270. 1906. 



