272 CALIFORNIA ACADEMY OF SCIENCES. 



anomala, Jjhiercus Gambcllii and Celtis occidentalis grew 

 where the soil was less alkaline, where the wash from the 

 sandstone canon walls mixed some sand with the clay; 

 but for miles near the lower end of the canon, Sarcobatus 

 vermiculatus, Gray ia polygaloides, Artemisia tridentata, 

 Suceda Torreyana, and various species of Atriplex almost 

 exclusively covered acres with a gray -green vegetation. 

 A few cottonwoods and willows were seen occasionally, 

 most abundant in the neighborhood of Hill's Ranch, near 

 the Colorado-Utah boundary and off the main road. 



Towards evening of the second day we reached the San 

 Juan River. The bluffs on the other side of the river, 

 visible for many miles, had inspired us with fresh vigor, 

 in the hope of good water and rest under the shade of 

 the trees. There was very little vegetation on the dry 

 mesas above the McElmo; occasionally a ravine would 

 store enough moisture to keep a few plants alive, such as 

 Wyethia scabra and Amsonia angustifolia Texana. We 

 were near camp when Mentzelia pumila began to open 

 out its starry blossoms; Heliotr opium convolvulaceum was 

 rare ; and Cladothrix lanuginosa spread its small mat down 

 here and there; Eriogonum Jlexum and cernuum, Gilia 

 Gunnisoni, pumila and leptomeria were abundant occa- 

 sionally on clayey flats which received the wash from the 

 hills, but they were not always found associated together. 

 Generally one species monopolized the ground on one 

 wash, another somewhere else in a similar situation. 



Near our camp on the San Juan the cottonwoods 

 ( Populus Fremontii Wislizenii ) were abundant; Rhus 

 Canadensis, Forestiera Neo-Mexicana and Salix lasiandra 

 Fcndleriana formed clumps here and there ; while Gilia 

 longiflora, aggregata and multijtora, Castilleia linaricefo- 

 lia, Cordylanthus Wrightii and Aplopappus gracilis were 

 the most noticeable herbs under the trees. D i cor ia Bran- 



