150 THE SALTON SEA. 



a month, and at the end of this time some generation of the radicles of two was noted, 

 and the lot was "stranded" in soil saturated with Salton water of 1913. None survived, 

 and it is probable that the time of actual flotation without injury is somewhat less than 

 a month and that the conditions for establishment were unfavorable in any one of a dozen 

 features. The fact that the seedlings float at all and come to the surface would make this 

 plant more liable to be carried about than the mesquite, which, as described on page 149, 

 does not free the seedling in the manner of this species. Pods taken from a tree in Feb- 

 ruary 1913 sank to the bottom. Neither the seeds in these, nor in others freed from them, 

 showed any action in a month; and no suggestion is to be made as to the agencies which 

 might, be cooperative with flotation in facilitating dissemination. 



The screwbean was a marked feature on the steeper beaches laid bare on Obsidian 

 Island and at the Travertine Terraces, where it has been found since 1907. Plantlets 

 were seen late in the autumn on strands laid bare during the summer, presumably from 

 seed of the preceding season. The greater number were immediately off the cut bank, 

 marking the mid-winter stage of the water, and as the seeds are too large to be carried by 

 the wind, and as they also sink, the presumption is in favor of the suggestion that seedlings 

 are carried to the place by the waves. (Plate 29 a.) 



Rumex berlandieri is a perennial which appears to reach maturity during the first 

 season in the Salton region and plants may be found in bloom from May to October or 

 November. The fruits, consisting of ovoid achenes inclosed in the sepals, may be held on 

 the stems for several months, and their average weight is about 1.5 mg., of which the 

 achene makes at least two-thirds; 100 of these fruits, from a dried specimen collected 

 near the lake in February 1908, were thrown into a dish of Salton water on November 25, 

 1912; 5 sank on the next day and a few more went down daily, until half were on the bottom 

 of the dish a week after being wetted. Germination began a week later with those still 

 remaining afloat and continued for over a month, at the end of which time the plantlets 

 formed a tangled mass. Near the end of this time the seeds at the bottom began activity 

 and the young plantlets rose to the surface, as a result of the formation of gas in the green 

 tissues. The germination of the entire lot extended over a month. A lot of twenty achenes 

 was separated from the calices and thrown into the water to ascertain whether or not 

 flotation was due to the seed or the adherent structures. All but one sank within three 

 days and this one was probably defective. Nearly all had germinated within a week from 

 the time they were wetted, although the temperature was now higher than when the origi- 

 nal lot was tested. The plantlets rose to the surface as they attained some size, although 

 three that were entangled with some debris on the bottom of the dish remained there 

 without injury for a fortnight. 



Two months after the first germinations had taken place a tangled mass of plantlets 

 was "stranded" on loam saturated with Salton water and many survived and sent down 

 roots into the soil. The soil, however, was moistened with Salton water taken from the 

 lake in 1912 and the plants soon perished. The long flotation of the plant is a condition 

 that would allow it to be carried great distances by wave-action or by currents, and doubt- 

 less introductions would result from the stranding of water-borne seedlings which might 

 be grounded on soil the water of which was not too high in salts. Confirmation of these 

 suggestions is afforded by the behavior of the plant on the beaches. Up to 1908 it was met 

 frequently in various localities, but after this time it did not appear until 1911, when the 

 shore being laid bare at Imperial Junction had been overlaid by silt from the Alamo River, 

 in the Delta of which it was very abundant. 



Scirpus paludosus did not appear on the shores of the lake until 1908, when it was 

 seen on the Imperial Junction beach. The plant was apparently carried the full length 

 of the lake during the year and came onto the beach at Mecca in 1909, while it did not 

 figure among the pioneers on the Travertine Terraces until 1911, although Scirpus olneyi 



