50 



bution centers is Pcpcromia maaiiosa. It was first seen growing 

 under the shade of Pinus occidentalis, on a mountain slope that 

 except for this Peperoniia might be considered edaphically 

 xerophytic. Not until our descent from the ridge of the Maestra 

 did we find it again, when a fair representation was seen in an 

 almost identical situation and at approximately the same altitude. 

 Its absence on a number of such mountains that we visited, and 

 its occurrence on these particular two, would seem to conform to 

 no well-known law of distribution. 



The method employed by the forestry expert in getting an 

 idea of the timber value of an area is perhaps the best possible 

 way to gather data on the tree distribution. From a study of 

 these notes and figures,* we came to know the frequency of 

 occurrence and characteristic habitat of the commercially more 

 important trees. But the number of exceptions, and the lawless- 

 ness of the occurrence of the monotypic species, together with 

 the equally inexplicable "species centers" make it dangerous to 

 draw any conclusions. Indeed it is practically impossible to 

 form any law that can reasonably account for the distribution of 

 even a small number of the species in this region. 



Although it is very difficult, perhaps impracticable, to get any 

 real idea of the distribution of the species, it is quite possible to 

 get some notion of the factors that govern the occurrence of the 

 various plant associations. From topographic and climatic con- 

 ditions that have been elsewhere more fully described, f we have 

 in these mountains two well-defined ecological areas : the coun- 

 try lying on the southern slope, which is mostly dry, and the 

 country on the northern slope and ridge. The latter is the wind- 

 ward side of the range and the strong Northeast Trade deposits 

 most of its moisture here, leaving very little for the leeward and 

 drier southern exposure. This has, of course, an obvious effect 

 on the vegetation, and by this is meant not so much the diversity 

 in the species, although this is great, as the marked difference 

 existing in the general vegetative or floristic character of these 

 contrasted situations. 



* Fernow, B. E. The High Maestra. Forestry Quarterly 4 : 250. 1906. 

 t Fernow, B. E. Loc. cit. 239 ; Taylor, N. Collecting in the Mountains west 

 of Santiago, Cuba. Jour. N. Y. Bot. Garden 7 : 256. N 1 906. 



