DEPARTMENT OF BOTANICAL RESEARCH. 



65 



Generally speaking, the alterations consisted in changes from 

 banded or crowded strand-formations (in which the most important 

 agencies affecting the plants were moisture and salt content) to the 

 open desert formations. Species of Atriplex, Spirostachys, Suoeda, 

 Heliotropium, Pluchea, Populus, Salix, and Sesuvium were among the 

 earliest arrivals on bared areas, but within two years Isocoma, Paro- 

 sela, Eriogonu77i, and others would appearand these would persist and 

 perhaps be found on ancient beaches. Thus, of the total ampHtude 

 of change from a moist saline beach to a dry desert ridge in a few 

 centuries much the greater part takes place with great rapidity and 

 within three or four years after the water has receded from the level 

 of its upper surface. 



The total census of the several observational areas from 1907 to 

 1913 inclusive comprised 61 species, as follows: 



Amarantus palmeri. 

 Aster spinosus. 

 Aster exilis var. australis. 

 Astragalus limatus. 

 Atriplex canescens. 

 Atriplex fasciculata. 

 Atriplex hymenelytra. 

 Atriplex lentiformis. 

 Atriplex linearis. 

 Atriplex polycarpa. 

 Baccharis glutinosa. 

 Bouteloa arenosa. 

 Chamaesyce polycarpa hir- 



tella. 

 Chenopodium murale. 

 Coldenia plicata. 

 Conyza coulteri. 

 Cryptanthe barbigera. 

 Cucurbita palmata. 

 Cyperus speciosus. 

 Elclipta alba. 

 Eleocharis sp. 



Encelia eriocephala. 

 Encelia frutesc-ens. 

 Eriogonum deserticola. 

 Eriogonum plumatella. 

 Eriogonum thomassii. 

 Franseria dumosa. 

 Heliotropium curassavicum. 

 Hilaria rigida. 

 Hymenochloa salsola. 

 Isocoma veneta var. acra- 



denia. 

 Juncus cooperi. 

 Lepidium lasiocarpum. 

 Lippia nudiflora. 

 Leptochloa imbricata. 

 Oenothera scapoidea auran- 



tiaca. 

 Oligomeris glaucescens. 

 Olneya tesota. 

 Parosela emoryi. 

 Parosela spinosa. 



Phragmites communis. 

 Pluchea camphorata. 

 Pluchea sericaa. 

 Polypogon monspeliensis. 

 Populus macdougallii. 

 Prosopis glandulosa. 

 Prosopis pubescens. 

 Psathyrotes ramossissima. 

 Rumex berlandieri. 

 Salix nigra. 

 Sesuvium sessile. 

 Scirpus americanus. 

 Scirpus olneyi. 

 Scirpus paludosus. 

 Sonchus asper. 

 Sonchus oleraceus. 

 Spha^ralcea orcutti. 

 Spirostachys occidentalis. 

 Suaeda torreyana. 

 Typha angustifolia. 

 Wislizenia refracta. 



Modifications of Plants under the Specialized Conditions Presented by Emersed 

 Strands, by D. T. MacDougal. 



The disturbances in the Salton Sink following the making and the 

 desiccation of the lake were of course followed by the exposure of 

 many species to unusual intensities of substances, the action of which 

 would have the direct effect of coagulating or hydrating the colloidal 

 substances of the plant body. But little attention could be given to 

 exact measurement or estimation of the effect, but noticeable devia- 

 tion in leaf and stem characters were observed in 3 of the 61 species 

 which occurred on the strands. These were Aster exilis, Prosopis 

 glandulosa, and Atriplex canescens. The thickish stems of the modi- 

 fied asters were strikingly suggestive of the hydration effects of 

 alkalies which may be taken to underlie the induction of succulency 

 in the higher plants. In addition to these modifications, species of 

 salt-bush {Atriplex saltonensis) and of spurge (Chamaesyce saltonensis) 



