Botanical Ecology of the Dry Tortugas. 



129 



same species from other keys. At any rate, the flora of the island is 

 quite varied and well scattered. Singular as it may seem, it is on this 

 island that more young plants of the red mangrove were found than on 

 any other island in the Tortugas. The south shore has many small 

 seedlings and in a landlocked tidal pool there is quite a clump of older 

 mangroves, which are perhaps 3 or 4 years old and seem to be hi a 

 flourishing condition (see plate 6). This pool also contains a con- 

 siderable school of small fish and some crabs. 



This key is the main nesting-place in the Tortugas for that beautiful 

 and graceful little sea bird, the least tern. All along the beach near 

 the young mangrove plants one stumbles suddenly upon the pairs of 



^ 1. Alternanthera maritima. 



^ 2. Atriplex cristata. 



+ 3. Cakile lanceolata. 



A 4. Cenchrus incertus. 



5. Chamaesyce buxifolia. 



| 6. Cyperus brunneus. 



j*; 1. Ipomoea pes-caprae. 

 X 8. Rhizophora mangle. 

 O 9. Scaevola plumieri. 



A .10. Sesuvium portulacastrum 



3 .11. Suriana maritima. 



f 12. Tournefortia gnaphalocles 



W 13. Uniola paniculata. 



Bush and Long Keys. Two inches = one-fifth statute mile. 



speckled eggs, which are very difficult to see as they lie on the bare 

 coral sand. Later the downy chicks are just as difficult to perceive, for 

 at the approach of a stranger they instantly become motionless balls 

 of gray fluff. These least terns are the only birds nesting on the island. 

 The western shore terminates in a long and narrow northern and 

 a broader and more rounded southern arm. Cakile and Cenchrus 

 incertus grow along the beach at scattered intervals. Back of this and 

 stretching east to the tidal pool is a thick aggregation of Uniola, 

 Tournefortia, Iva, and a little Suriana. East of the pool is a sparse 

 growth of Atriplex, Sesuvium, Ipomoea, Cakile, and Alternanthera. 

 South of the pool and in a line with the highest tide-levels are the young 

 Rhizophora seedlings. These seedlings and those about the pool were 



