MAYOR— ROSE ATOLL, AMERICAN SAMOA. 63 



Pisonia grand is trees, casting so complete a shade that no other 

 plants grow beneath them, save only a single cocoanut i)alm, which 

 was probably planted by Governor Tilly's party about fifteen years 

 ago. This forest forms a nearly symmetrical dome, the leaves and 

 branches on its confines extending quite to the ground. The largest 

 trees are near the southern end of the grove, and about three feet 

 above the ground one of these trees had a girth of 25 feet 7 inches, 

 and was about 80 feet high. The ground under these trees is cov- 

 ered with a rich chocolate-colored humus, which is of considerable 

 depth near the southern end of the grove. 



Apart from this grove of pisonia trees and a half dozen cocoanuts 

 planted by Governors Tilly and Terhune in 1902 and 1920, there are 

 only two other species of plants upon the islet. These have been 

 identified by Professor William A. Setchell and are a pink-flowered 

 creeping Boerlmaz'ea diffusa with stems rarely more than 3 feet 

 long; and a thick-stemmed succulent Portulaca n. sp. with small 

 yellow flowers. Both of these plants grow fully exposed to the sun 

 on the coral breccia and calcareous sand which surrounds the pisonia 

 grove, and none are found under the shade of the trees. 



On the south side of Rose Islet the sand beach is reduced to 

 from I to 5 feet in width at low tide, and clififs of coquina from 5 

 to 8 feet high front the sea. A few feet inland this rocky ledge 

 rises to a height of about 11 feet above high tide level. The 

 pisonia grove appears to be confined to this region of coquina rock 

 and does not appreciably extend out over the loose calcareous breccia 

 which has been washed in upon the islet in time of storm. 



The tree-covered rocky center of the islet is composed of a 

 coquina consisting chiefly of wave-worn fragments of lithotham- 

 nium, and also rare and occasional pieces of broken coral such as 

 Favites, Porites, SympJiyllia, Pocillopora, and still more rarely 

 Acropora. Imbedded in it are many wave-worn half-valves of 

 Tridacna, and Gasteropod shells, and spines of Echini such as 

 Cidaris were found, as was also the much-corroded ulna and part of 

 the skull of a small Cetacean about the size of a black-fish, the latter 

 being embedded in the coquina al)out 8 feet above high tide level. 

 A lars:e amount of orijanic matter dark brown in color and derived 



