Botanical Ecology of the Dry Tortugas. 131 



times by the author durmg 1915 and 1916, and at the first visit he 

 noted near the central portion of the key one plant of Sccevola and two 

 plants of Iva imhricata. These seemed to be growing and flourishing. 

 Dmdng July, in 1915, several visits were made and on the last occasion 

 only one dead Sccevola plant and several dead Cakile plants were found. 

 There was nothing alive on the island but a few hermit crabs and some 

 sea birds fishing near the beach at the western tip of the island. The 

 sand was so hot at mid-day that, after walking over the island a few 

 minutes, shoes had to be removed and the circuit of the island com- 

 pleted by wading. With this incident as an illustration, it is seen 

 that only the hardiest plants can live on these bhstering sand islands. 

 In Lansing and Millspaugh's paper, Lansing noted 5 species, fairly 

 well scattered over the island — Uniola in the north, Sesuvium in three 

 groups on the east, and Iva along the west shore, the central area being 

 fiUed with Ipomcea and Chamcesyce. Since March 21, 1904, then, the 

 whole island must have been denuded of vegetation and the three 

 species noted by the author have come in lately. All the plants have 

 gradually succumbed to the hard conditions on the island. Of Lan- 

 sing's species, only Iva imhricaia was found by the author; Sccevola 

 and Cakile were not reported by him as being there at that time. 



MIDDLE KEY. 



Next to Sand Key, going east, is Middle Key, the smallest of the Dry 

 Tortugas islands. It is little more than an oval patch of sand, about 

 80 feet long by 50 feet wide. Millspaugh states that Lansing found no 

 vegetation on Middle Key whatever and that it is so low that, hke 

 Long Key, it is awash in rough weather. Notwithstanding the possi- 

 bilitj'^ of the last statement, the author found several large tufts of 

 dead Cakile on the key, its season having passed in Jul5^ It is reason- 

 able to suppose that the island has been built a little higher in the past 

 12 years by the current action, and especially so since the general map 

 accompanying the paper shows that Middle Key is built, as are indeed 

 the others, on quite extensive shoals scarcely submerged. 



EAST KEY. 



This is the most outlying key of the group since the disappearance of 

 North and Northeast Keys a few j^ears ago. It is the largest of the 

 three keys stretching northeast of Garden Key and is al^out 4.5 miles 

 from the latter key, about one-third of a mile in length and less than 

 half that in width. It is almost entirely covered with ^'egetation and 

 shows several associations as outlined in this paper. Cejichrus and 

 Cakile are disseminated thickly along the shores, the latter particularly 

 along the southeast shelf of dry sand-beach. Uniola and Chamcesyce 

 are in fairly thick growth on tlie northern and southern ends, with a 

 sprinkling of Uniola all along the western side. Townefortia, as large, 



