154 THE SALTON SEA. 



Atripkx hymenelytra is native to the upper slopes of Obsidian Island and it was seen 

 to follow down the slopes on the steeply sloping beaches. It is not known whether the 

 fruits could be transported by flotation or not. The suggestion lies near that its survival 

 may be determined very largely by the composition of the soil. 



Atripkx linearis was one of the four species of this genus which appeared among the 

 earliest occupants of the alkaline strand at Imperial Junction beach; but if present after 

 that year, it was represented by so few individuals as to escape observation. 



Atripkx polycarpa, which ordinarily forms a shrub less than 3 feet in height, was 

 observed but three times on the emersions, one on the beach of 1907 at Mecca and on the 

 beaches of 1907 and 1908 at Travertine Terraces. It did not survive beyond the season 

 and its general behavior here may be correlated with the fact that it ordinarily is found 

 on rather dry soils, not very highly charged with salts. 



Bouteloua arenosa appeared on the emersion of 1907 on the western side of the lake, 

 and^also upon the strand of 1908 at the Travertine Terraces, but it soon disappeared 

 from both places. 



Chamcesyce polycarpa hirtella appeared on beaches on the western side of the lake in 

 1908 in places in which it might readily have been carried by run-off streams. The rapid 

 widening of the beaches upon the gentle slopes, however, was not followed by its appear- 

 ance a second time. 



Chenopodium murale was found on the gentle slopes of the beach laid bare at Mecca, 

 as seen in February 1908, but it could not be found there three months later. A second 

 occurrence was noted on Imperial Junction Beach in October 1909, but the plant did not 

 become established in either location. The seeds seem to be subject to the action of many 

 carrying agencies, as it is to be seen in many widely separated parts of the world. Follow- 

 ing these observations, it was next noted by the author along Khor Adit, leading down into 

 the Red Sea, at an elevation of 1,500 feet, in northern Sudan. 



Conyza coulteri was found in the emersion of 1907 at Mecca, during the visits of 

 February and May 1908, but did not appear as a constituent of the beach flora on any 

 subsequent occasion. 



Coldenia plicata was found on the ground laid bare in 1907 on the western side of the 

 lake, but no further participation in the occupation of the beaches was noted. Mature 

 plants fell with the masses of soil onto the beach of 1907 at Travertine Terraces, but appar- 

 ently all died; although seeds of this plant must have been sown on other beaches here, 

 none survived. 



Cryptanthe barbigerawas found on the southeast shore of Obsidian Island in such position 

 with respect to the high level of the water as to give rise to the inference that it may have 

 been carried there by birds. The burr-like fruits might readily become attached to feathers or 

 carried on muddy feet. Although maturing fruits were seen, no reproduction occurred. 



Cucurbita palmata inhabits the dry gravelly slopes of the Sink and has been seen on 

 the bajadas west of the lake, maturing fruit in late summer or in mid-winter. The globular 

 fruits have a hard outer shell and are very light, in consequence of which they may be rolled 

 about by the wind, carried by small run-off streams, or floated by the lake. 



This species was introduced more than once at Imperial Junction beach, but did not 

 survive long there. Neither here nor on the gravelly beaches of Obsidian Island did it come 

 ashore later than 1909. The defection might be partly due to two causes: the supply of 

 fruits which would be brought onto the waters of the lake would decrease with the recession 

 of the shore line, and the increasing salinity of the water would be injurious to the seeds- 

 this last point was not tested. The plant survives in the emersion of 1909 on the gravelly 

 beach of Obsidian Island, which furnishes the conditions of its usual habitat The size and 

 character of the fruit are such that it may be said with certainty that it has been trans- 

 ported only by flotation to the islands or to Imperial Junction Beach. (See Plate 29 a ) 



