MOVEMENTS OF VEGETATION IN THE SALTON SINK. 151 



had been seen there in the two preceding years. Nothing is known as to the part played 

 by propagative bodies in this dispersal. It is to be recalled that the species was not noted 

 on the shores of any of the islands. 



Scirpus paludosus is a bulrush first known from the upper waters of the Colorado 

 River, and since it was not included in many collections along the lower courses of the 

 river more than twenty years ago, it seems reasonable to assume that its flotation down 

 stream and into the Delta (see Parish, page 106, this volume) is a comparatively recent 

 matter. Nothing may be said as to the causes which may have set up the distributional 

 movement. No question remains, however, as to the fact that it is now much more widely 

 disseminated than a few years ago. The three-angled flattened achenes weigh 3 mg. and 

 they come free and clean when mature. Mr. S. B. Parish collected a supply in the Sink 

 in October 1912 and 100 of these were placed in Salton water November 16, 1912. All 

 floated at first and none showed signs of wetting or of absorption of water until the 25th, 

 when a few were seen adhering to the walls of the glass vessel. A day later some were 

 water-logged and remained immediately beneath the surface. Shortly one sank to the 

 bottom, and this process continued so that 14 were on the bottom on December 14, a 

 month after being thrown into the water, while the total number on the bottom was but 

 24 on January 19, 1913; about 31 in all went to the bottom, where they remained for ten 

 days, when some of these, as well as some on the surface, germinated and the number 

 increased so that 17 seedlings were counted on March 17, and these were all on the surface. 

 Some which had been floating a month were now "stranded" in a dish in which the water 

 was that taken from the Salton in February 1913, and it was seen from the first that their 

 survival was assured. Sound plantlets were seen on the water as late as April 4, six weeks 

 after germination. A large number of sound seeds remained, some floating and some on 

 the bottom. It is to be seen from this that the flotation properties of either the seeds or 

 of the seedlings would be an important factor in the dissemination of the plant, and would 

 easily account for its presence in the Delta or any place in the Sink. Some unusual charac- 

 ters of fruits were displayed by the plants of this species collected from the Salton beaches. 



Sesuvium sessile is the prostrate sea-purslane of the beaches and saline areas of widely 

 extended territory. It blooms during the entire warm season and seeds may be collected at 

 almost any time in the Salton region. These are extremely small, weighing only 0.04 mg. 

 A supply was procured in October 1912 and 100 placed in a dish of Salton water on Novem- 

 ber 16, 1913. All floated until December 9, at which time (23 days after being put into 

 the water) 1 had germinated and 13 sank upon shaking. All sank by January 13, 1913, 

 and the original seedling was still alive, no other germinations having taken place. With 

 the coming of warm weather the outer coats were shiny with a thin layer of collected gas 

 and they began to rise to the surface, where all were floating on January 26. Germinations 

 now began and apparently all of the sound seeds had sprouted by February 10. A lot 

 were "stranded" on February 15 and a large number sent roots down into the saline soil 

 and were quickly established under terrestrial conditions. 



It is evident that the behavior of the seeds is such that they might be carried in almost 

 any manner about the lake, and the species appeared on emersed beaches soon after the 

 son* was bared in the main observational areas; it is also included among the small number 

 found on sterilized islands. Like nearly all succulent halophytes, it does not survive long 

 in desiccated soils. 



Spirostachys occidentalis is a succulent halophyte which occurs in saline areas in this 

 region. The seeds are retained indefinitely after maturity, and hence it was possible to 

 secure a supply of the crop of 1912 from plants near Mecca as late in the season as Feb- 

 ruary 7, 1913. Some were thrown into a vessel of Salton water on February 14 and all had 

 sunk within 24 hours. Germination began within the second day, and all of the perfect 

 seeds had germinated within 100 hours after wetting. The seedlings soon began to rise to 



