212 Flora of Boitldin Island. [zoe 



the bottom of the river, and is added to year by year, as it is con- 

 stantly sinking. Both sides of the levee are fringed with a dense 

 growth of willows, alder, and the ever present "Tule." The 

 land slopes to the centre and is irrigated by means of guarded 

 openings in the levee, care being taken not to admit an undue 

 quantity of water. The island is dry on the surface for the most 

 part, although the water is but a short distance beneath, and the 

 winds often raise the light loam from the roads in swirling clouds 

 of dust. The ground shakes very perceptibly from the passing 

 of wagons, and in many places even from a footstep, a peculiar- 

 ity which is somewhat unpleasant until custom has rendered it 

 familiar. 



The natural flora of the islands embraces but few species as 

 would naturally be expected from the sameness of environment. 

 It consists besides the prevailing " tules " — Scirpus lacustris and 

 ^. Tatora — in great part of Psoralen macrostachya, Epilobiuvi 

 holosericeum, Solidago occidentalis and ^S. elongata, Baccharis 

 Doiiglasiii Helianthiis Calif ornicus , Artemisia vulgaris, Apocyiiuvi 

 cannabinum. Convolvulus Sepium, Stacliys albens, Polygomivi 

 Hartwrightii, Urtica holosericea, Alnus viridis, Salix longifolia & 

 S. sessilifolia, Typha latifolia, Cyperus erythrorhizos, Phragniites 

 communis, etc. The leveed islands abound in weeds as may be 

 seen from the list appended. Their luxuriance in most cases far 

 exceeds anything seen on the mainland, and the species are 

 usually well diffused.' The vegetation is late, the time of fullest 

 flowering being in August and September. 



The entire absence of many of the large genera and even 

 families of Californian plants of the not distant mainland is very 

 noticeable. Ranunculus aquatilis is the only plant belonging to 

 that family to be expected, and even that has not been collected 

 on Bouldin Island. There are no Caryophyllaceae except a stray 

 Silene Gallica or Stellaria mediae no violets, no Saxifragaceae, no 

 Hydrophyllaceae, no Polemoniaceae except an occasional recently 

 immigrated Gilia sqiiarrosa, not a single Hemizonia or Eriogonum, 

 and no plant belonging to the Orchidacese, Iridacese, or Liliacese, 

 unless Lilium pardali7im}i should be found to occur in some 

 places. 



The list below is the result of a visit to Bouldin Island, Sep- 



