162 THE SALTON SEA. 



for germination of deposited seeds. Next it is to be recognized that the crop of seeds, 

 such as those of Populus, Salix, or Pluchea, may mature and be freed from the plant all 

 within a comparatively brief period, during which time the number carried about by the 

 wind would be distinctly noticeable. Thus the few days in which the fruits of Populus 

 are in the air serve to distribute them in such number that they may become an annoyance 

 by clogging wire mosquito screens, or by passing into houses through open doors or windows. 

 It is evident that strands would be thickly strewn during the fortnight in which these 

 seeds are so thick in the air and that this plant might be entirely absent from the remainder 

 of the emersion of the year unless seeds or fruits falling on the water were capable of sur- 

 viving the effects of such flotation and saline action. 



Still another phase of wind-deposition of seeds was presented by the Travertine Ter- 

 races, which are characterized by a strict rank of vegetation arising at the foot of the 

 higher well-defined cut bank formed in mid-winter as well as the base of the more indefinite 

 ledge which may be made in mid-summer. The vertical surface of the cut bank, being 

 composed of moist earth and of the flotsam collected at the base on a slope that drops 

 away slightly (making an angle greater than a right angle), a mechanical trap is formed 

 causing eddies and other effects and resulting in deposition of wind-borne bodies including 

 seeds. (Plates 25 b and 26.) 



A visit was made to this place on February 8, 1913, when an unusually high-cut bank 

 was observed which might have been formed by wave-action of more than average violence 

 or to a greater recession of the lake level. The face of the vertical wall of soil which was 

 caving and falling down ranged from a few inches near the margins of the observational 

 area to a height of 26 or 28 inches at the crest of the slope which they cut across. The water 

 was comparatively quiet, but the wavelets were still lapping against the base of the mud 

 wall, and here was massed flotsam consisting of feathers, shells, and fragments of wood of 

 more than one kind and other fine material, among which some seeds might be expected. 



About two pounds of this material were taken up from a line extending about a yard 

 along the bank, put into a waterproof covering, and carried to Tucson. Some glass jars 

 were filled with a commercial quartz sand and this was saturated with Salton water taken 

 from the lake in October 1912. The debris was now spread on the surface and enough 

 water added to float it. The preparations were placed in a glass house at a temperature 

 of about 50° to 80° F. The first germination appeared 11 days after the preparations 

 were made, and the first plantlet developed was an Atriplex; a grass started into activity 

 a week later and a second grass was included in the final fist of germinations. By March 

 20, a month after the first seedlings had appeared, 20 germinations had taken place. The 

 rising temperature made it necessary to water the preparations and in this process the 

 fragments of wood on the surface were moved about by the water in such manner as to 

 destroy six of the seedlings; a second watering resulted in the death of two more. The 

 sand in which the plantlets were growing would have been moistened by water from under- 

 neath on the beach, and the fatalities noted would have probably been less at this stage 

 of their development than in the experiments. It is quite probable that the greater num- 

 ber of the seedlings which were killed before identification were Sesuvium or Heliotropium. 

 A visit to the place late in May showed a large number of seedlings of Salix and Populus 

 besides a few of Heliotropium, Cyperus, Atriplex, Prosopis, and a grass. 



The results of these tests suggest that the willows and poplars which come into the 

 rank at the base of such vertical walls made by the waves must be wind-borne. While 

 about 50 of the 60 species appearing on the Salton beaches might owe their presence to 

 the action of winds, nevertheless other agencies display great effectiveness; a rough eval- 

 uation of the balance of forces will show a number in which the seeds might be carried 

 by the wind only, and in such a list there would be included Aster spinosus, A. exilis var. 

 australis, Baccharis glutinosa, Encelia eriocephala, Isocoma veneta var. acradenia, Pluchea 



