Botanical Ecology of the Dry Tortugas. 123 



the laboratory. Melanthera hrevifolia has migrated all along the path 

 leading to the laboratory end of the key and has also spread into the 

 association of Opuntia, while Cyperus and Calonyction occur over the 

 central portion cleared of Suriana. The old grove of Sebesten {Cordia) 

 has not changed in area or spread. Hymenocallis is now disseminated 

 fairly well over the island, having been planted largely along all 

 the walks and paths, as well as the coconuts and Casuarina. Salvia 

 serotina is found only about the light-house, and Capraria biflora is not 

 widely scattered. The shrub Cerbera thevetia (which has been planted 

 for the decorative effect of its beautiful yellow blossoms) and the 

 weeds Poinsettia pinetorum and P. cyathophora were probably intro- 

 duced with soil brought from the mainland of Florida. 



In summarizing the distribution on Loggerhead and comparing it 

 with Lansing's account, the most conspicuous facts are the disappear- 

 ance of a large amount of Suriana from the central portion and the 

 spread into this area of the Opuntia group, the increase of Uniola, and 

 the disappearance of Guilandina {Ccesalpinia) crista, Iva imbricata, and 

 Tribulus cistoides. The appearance of the island is changed on account 

 of the large number of trees and shrubs and other plants introduced for 

 decorative and utilitarian purposes. A comparison of the hsts also 

 shows various differences in nomenclature due to synonymy, together 

 with one systematic discrepancy, viz, Cakile fusiformis, as listed b}'' 

 Lansing and Millspaugh, is evidently C. lanceolata (Wild.) 0. E. Schulz. 

 C. fusiformis, while indigenous to the keys, has not been noted in the 

 Tortugas. The number of seeds in the pods of the Tortugas species 

 place it as C. lanceolata. The total number of species on the island at 

 present is 41, as compared with Lansing's list of 24. 



BIRD KEY. 



Bird Key, which is considerably smaller than Loggerhead, is only 

 about 500 feet long by 300 feet broad and is now a government bird 

 reservation for the sooty and noddy terns. These birds nest on this 

 small island during the summer months. During the breeding-season 

 for many years this key has been almost covered by these terns, which 

 are now protected by the United States Government and the Audubon 

 Society, and for this purpose a warden is stationed on the island from 

 April to the end of August. 



The writer can scarcely estimate the effect produced upon the vege- 

 tation of the island by the presence of the birds in such large numbers 

 during the summer and in recent years of the warden, but as the birds 

 live entirely on fish and the warden does nothing to change the physical 

 character of the key these influences do not seem to be of great impor- 

 tance; but since Lansing's survey, in March 1904, a considerable 

 change must have taken place. 



