FEB. 1907. FLORA SAND KEYS OF FLORIDA MILLSPAUGH. 213 



MARQUESAS "D" 

 MARCH n, 1904 



Ambrosia hispida (2145) 

 < Borrichia arborescens (2155) 

 if Caesalpinia crista (2154) 

 Cyperus brunneus (2152) 



Ernodea littoralis (2156) 

 Euphorbia buxifolia (2143) 



n . Laguncularia racemosa (2151) 



H Lantana involucrata (2144) 



Melanthera nivea (2148) 



A Pithecolobium guadalupense (2147) 



3 Rhizophora mangle (2141) 



Rivina humilis laevis (2146) 



D Solanum bahamense (2149) 



F Sporobolus virginicus (2153) 



f Suriana maritima (2140, 2142) 



1 Uniola paniculata (2150) 



This odd, helmet-shaped islet presents a peculiarly clear-cut com- 

 panionship*of the species forming its flora. In extent it is about 150 

 by 75 feet with an elevation of about 4 feet throughout the central 

 plateau. Its high sea border is almost sheer, while its plateau gently 

 slopes into the mangrove swamp that characteristically faces the inner 

 shallows of the group. 



The Uniola-Euphorbia-Cyperus association exhibits the usual fea- 

 tures with no exception whatever, but beyond this the groupings are 

 striking. The central position of the Ambrosia which is almost always 

 found on the immediate strand; the strongly separated colonies of 

 Sporobolus; the entire absence of Sesuvium when its presence would 

 certainly be expected; and the clear-cut isolation of the various 

 colonies, that habit the slope between the plateau and the mangroves, 

 marks a vegetal problem that can only offer as a solution the youth 

 of that portion of the islet between the mangroves and the plateau. 



