JOHNSTON: FLORA. OF MARGARITA ISLAND. 281 



In connection with this discussion there is an interesting field for 

 study in the distribution of the individual species of plants whether 

 in groups or singly, whether in one place or scattered in many, and 

 whether on one slope and not on another. 



The species of plants found on the seashore and by the lagoons are 

 without exception growing in groups with but little intermixture. 

 Almost any of the plants illustrate this, Rhizophora, Avicennia, Batis, 

 Salicornia, and Trianthema. The species growing on the plains are 

 found in abundance though well interspersed with other species. So 

 far as was discovered Opuntia leptocaidis was growing in abundance 

 but over only a small area to the west of Porlamar. Similarly, Croton 

 Milleri was localized though well mixed with other plants. Many 

 of the plants were to be found in different locations, which, however, 

 had similar moisture conditions. This was even more accentuated 

 in the valleys and hillside than on the plains. While many plants 

 could be found in a fairly large quantity, the majority of the hillside 

 plants occurred in small numbers. Some plants which were found 

 only on the south slope of a hill might be found on the south slope of 

 another hill but not on the north side. Further detailed exploration 

 might tend to generalize this statement but the conditions as given were 

 rather striking to me. For example, Steriphoma elliptica occurs on 

 the south slope of South Hill and on the south slope of North Hill but 

 not on the other parts of the island so far as explored. Bauhinia 

 cumanensis occurs similarly. Cases of isolation are Securidaca only 

 on the north side of North Hill, Hymenea Courbaril on the south side 

 of South Hill and Pedilanthus on the summit of South Hill. 



The instances in which only two or three plants of a species were 

 found are few and it must be admitted that a thorough examination 

 of the hills and valleys in a better season would probably show more 

 of the plants. Notwithstanding this the paucity of specimens was only 

 too apparent to me when collecting, and it seems to be a fact that in the 

 majority of cases (striking exceptions are Tribulus, Stach^-tarpheta, 

 Jatropha, and Croton) the number of plants of the individual species is 

 very much smaller than is the case with our common plants of the United 

 States. Only one plant was found of Chiococca micrantha, a half 

 dozen near together of Securidaca, a single one of Hymenea, a single 

 tree of Acacia macracantha in San Antonio valley and three or four 

 along the river trail of El Valle, three plants of Oncidium luridum, 

 three of Huntleya, and three of Elleantlnis attenuatus. The list 



