230 FIELD COLUMBIAN MUSEUM BOTANY, VOL. II. 



flora of the Tortugas group. The great number of species on this bit 

 of sand, not differing in itself from that of the other islets, must be 

 due either to ballast dumping or some element connected with the 

 presence of man. Along the west beach is a stretch of Paspalum dis- 

 tichum with a sprinkling of Cyperus brunneus, two isolated patches of 

 Lithophila vermicularis, and beyond these to the southern extremity a 

 complete border of Uniola paniculata with a fringe of Cenchrus tribu- 

 loides at its seaward base. The southern portion of the point is given 

 up to Canavalia obtusifolia which is separated from the Uniola by a 

 growth of Euphorbia buxifolia. In the center of the spit is a hetero- 

 geneous intermingling of Ipomoea pes-caprae, Euphorbia btixifolia, Atri- 

 plex cristata, Bidens leucantha, Suriana maritima, Tournefortia gnapha- 

 lodes, Heliotropium curassavicum, Canavalia obtusifolia, Sida carpinifolia, 

 Melanthera nivea, Sonchus oleraceus, Eustachys petraea, Capraria 

 saxifragaefolia, Sesbania sericea, Sporobolus purpurascens, Euphorbia 

 adenoptera and Portulaca oleracea. Near an outbuilding, a few feet 

 from the base of the moat wall, is a clump of Opuntia Dillenii, a 

 cluster of Amaranthus viridis, and a patch of Boerhaavia viscosa; 

 between these and the board walk the space is occupied entirely by 

 Canavalia obtusifolia, terminating in one plant of Sesbania sericea. The 

 bit of sand between the walk and the east beach close to the wall of 

 the moat is occupied by the Canavalia, Argemone leiocarpa, Sonchus 

 oleraceus, Valerianodes jamaicensis, Iva imbricata, and immediately at 

 the beach Ipomoea pes-caprae. 



On the coping of the bastions grows the only implantation of 

 Euphorbia havanensis in the group; it is accompanied by Canavalia 

 obtusifolia and Melanthera nivea. 



