90 THE SALTON SEA. 



These two sources account for the greater part of the plant population of the Sink. 

 Some individuals belonging to the cafton-flora of the bordering mountains are sometimes 

 carried down by the flood waters, mostly as seeds, into the Sink, but they do not increase 

 or probably long endure. Travertine Rock, of which some account will be given farther 

 on, introduces a few montane plants. Two small "Cismontane islands" are formed by 

 small groups of Baccharis viminea at Dos Palmas and of Eriodictyon californicum at Indio. 



The endemic flora of the Colorado Desert is not extensive, and but few of its species 

 are found in the Sink. Of these Washingtonia filifera is the most important.^ 



DISTRIBUTION OF THE SINK FLORA. 



The distribution of the flora of the Sink is determined in dependence upon the edaphic 

 conditions outUned on a preceding page, and may be conveniently considered in its relations 

 to them. The term "formation" is applied to the wider groupings, and the term "associ- 

 ation" to the minor societies of which the formations are composed. 



HYDROPHYTIC FORMATION. 



The hydrophytes are very feebly represented in the flora of the Sink. The water of the 

 rivers and canals is so heavily loaded with silt as to prevent the growth of these plants and 

 the amount of clear water is very Umited. The springs, and the pools about them, are 

 nearly free from algae, such as commonly mantle the surface or float below it in similar situ- 

 ations elsewhere. Nor does one find the beds of dried pools coated with the felted filaments 

 of algse which had grown in the water. The few species which do occur are mostly to be 

 found in artificial pools and streams, such as are formed by the drip or waste of artesian 

 water, and even there they are not abundant. Occasionally a few filaments may be seen on 

 mud banks. No collections were made to determine the presence of desmids or diatoms. 



In only a single instance was a submerged spermatophyte observed. This was in 

 Salt Creek, between Seely and Dixieland, in the extreme southern part of the Sink. Salt 

 Creek is a shallow stream, some 50 feet wide, flowing between high and perpendicular 

 bluffs of alluvial soil, from the bases of which the salty water oozes by seepage. Its bed 

 is completely filled with a thick growth of Ruppia maritima. 



HELIOPHYTIC FORMATION. 



The heliophytic formation of the Sink is far richer in species and greater in extent 

 than the hydrophytic. It may be considered under two associations, that of the springs 

 at the upper or northern end of the Sink and that of the rivers and canals at the lower 

 or southern end. 



SPRINGS ASSOCIATIONS. 



The vegetation growing in the springs, of which there are several on both the east- 

 em and the western sides of the upper end of the Sink, is composed of two species of 

 very extended distribution, Typha latifolia and Scirpus olneyi. In none of them was there 

 apparent evidence of the presence of plankton or of any subsidiary associations. They 

 consist of pools, having little or no run-off, very thickly grown up with the two plants 

 mentioned. Short descriptions of three of these springs, each of a different type, will 

 suflSce to give an idea of all. 



MOBTMERB. 



Mortmere is near the northeastern end of the Salton Sea, at an altitude of about 200 

 feet below mean sea-level. Its position is marked by its clump of green vegetation, which 



' The following species are endemic in the Sink, so far as present knowledge of their distribution indicates, but 

 further exploration of the desert may be expected to extend the range of at lea.st some of them: Astragalus aridus 

 Gray, A. liinalus Sheldon, AlHplex saUonensis Parish, Chamwsyce saltonensis Millsp., Cryplanthe costata Brandg., 

 Spharakea orcuUii Vasey & Rose, PheUorina maarosperma Lloyd. 



