l:;7 



dominate particular elevations. Uiiiola, which is most abun- 

 dant, covers many of the ridges, Sporobolus virginict4S has pos- 

 session of others, and Paiiicum aiiianiin and Spartiiia polystacliya 

 occur in considerable quantit)'. Kearney has called attention to 

 a fact just mentioned — that each species seems to have complete 

 control over certain areas and a mixture of several is rarely seen. 

 Excluding the grasses, the vegetation is very scanty. Croton 

 niaritiiiiiis, Iva ivibricata and Salsola Kali are the only species 

 that seem capable of existing here. The Iva and the Salsola are 

 extremely succulent, the CrotoJi less so, but well protected by 

 shining scales. In the depressions behind the outermost dunes, 

 where moisture prevents the sand from being easily disturbed, 

 several other plants appear in addition to the ones just mentioned. 

 Euphorbia polygonifolia and Ooiotlicra Jiuniifusa are not rare in 

 such positions, and the troublesome grass Ccnchrus tribuloidcs is 

 abundant. LcptocJiloa fascicularis, a grass that is rather common 

 here, assumes among these outer dunes a very different form from 

 the specimens in more stable soil. Its branches are here long 

 and straggling and of a reddish color, while on the landward side 

 of the island it is much more delicate and turf-like. At certain 

 places the tide makes in between the outer ridges and floods the 

 depressions behind them. On the borders of one of these flooded 

 depressions I was delighted to find a beautiful growth of the trail- 

 ing tropical sand-strand plant Ipouioca littoralis (L.) Boiss., which 

 takes the place here which is generally occupied farther south by 

 the much more common Ipoiiioca Pcs-Caprac. In Fig. i is gixen 

 a photograph of this spot with Ipomoca littoralis in the foreground. 

 It will be noticed that the tips of some of the long runners are 

 submerged at high tide. As far as I can determine, this is as 

 far north as this plant has been recorded on our shores. The 

 other plants represented in the photograph are Spartiiia poly- 

 stacJiya, covering a little knoll in the middle to the left. Uniola 

 paiiic?ilata in center and left of background, Panicinn auiaruui in 

 background to right, and a few clumps of Salsola Kali in center 

 to right. 



In the somewhat sheltered depressions among the dunes there 

 are also present a few scattered specimens of Yucca gloriosa. 



