PLANT ECOLOGY AND FLORISTICS OF SALTON SINK. 



103 



ANALYSIS OF THE FLORA. 



Of the plants listed in the following catalogue 23 are sporophytes and 179 are sperma- 

 tophytes, a total of 202 species. The sporophytes are represented by 15 families and 21 

 genera. 1 The spermatophytes are represented by 43 families (21 of them having but one 

 species each) and 121 genera, 89 of which have but a single species each. Of the 179 

 spermatophytes, 131 are indigenous and 48 are introduced. All the introduced plants 

 except a few found on the beaches of Salton Sea, are confined to those parts of the Sink 

 which have been reclaimed through the economic operations of human settlement; in no 

 case have they been able to intrude where natural conditions remain. 



The largest families are: the Composite, with 25 indigenous and 12 introduced species; 

 Graminese, with 12 indigenous and 10 introduced species; the Leguminosse, with 10 indige- 

 nous and 2 introduced species; the Chenopodiacese, with 9 indigenous and 3 introduced 

 species; the Polygonacese, with 6 indigenous and 2 introduced species; and the Euphor- 

 biaceae, with 7 species, all indigenous. 



Genera having over three species each are: Atriplex 8, Chamcesyce 6, Eriogonum 4, 

 Parosela 4, and Sphceralcea 4. All the species are indigenous except one Atriplex. 



Disregarding 9 species which merely overpass the rim of the Sink, its indigenous flora 

 consists of 8 trees, 23 shrubs, 10 suffrutescent plants, 30 perennial herbs, and 51 annuals. 

 These indigenous spermatophytes may be divided in accordance with their habital character 

 into two classes: (1) those which grow only in water or in moist soils; (2) those which grow 

 in arid soil. The latter constitutes the flora of the absolute desert. Isocoma and the two 

 species of Prosopis are included in the second class, although they grow also in damp soils. 



A floral census evidently conveys an inadequate and incorrect presentation of the 

 phytogeography of a region if an equal value is given to species widely distributed and 

 abundant and those which are rare — a single specimen of the latter perhaps having re- 

 warded extensive explorations. With this in view an attempt has been made in the above 

 table to separate those species which are fairly frequent (at least in some parts of the Sink) 

 from those which are rarely seen. In making such a division the tabulator must needs be 

 guided largely by what he has himself observed, so that his results are subject to the revi- 

 sion of other and more extended investigations. Especially does this apply to the annual 

 herbs; for under the irregular meteorological conditions of the Sink an unusual season may 

 bring up in abundance annuals which in ordinary years make hardly any appearance. But 

 it is believed that, on the whole, those species which are indicated in the table as "frequent" 

 are those which the botanist will certainly find in more or less abundance in some part of 

 the Sink, though not in every part. 



It appears by the table that of the 79 xerophytes, 51 are common in some parts of the 

 Sink. The species which are abundant everywhere in the arid soils of the Sink are but two: 

 Atriplex canescens and Isocoma veneta var. acradenia. These two are also found in the 

 physiologically dry alkaline soils. In number of individuals they probably equal the united 

 total of all the other plants above the rank of herbs. 



1 The undetermined moss and two undetermined lichens are not included in this synopsis. 



