94 Muhlenbergia, Volume 5 



The hills and the uncultivated parts of the mesa are natur- 

 ally covered with a good growth of sage brush, but much of the 

 watershed of the arroyo has been rendered bare and barren by 

 repeated fires and the trampling of sheep. The mesa lands bor- 

 dering the arroyo from the foot of the hills to the river bank are 

 practically all in cultivation, either as grain fields or orange 

 groves, and even parts of the steep walls are terraced and 

 planted, leaving only here and there little patches of the origi- 

 nal vegetation. In its lower course both sides of the arroyo are 

 in the city of Riverside, and both bottom and sides are occupied 

 by houses, gardens and pleasure grounds, Chinatown being a 

 conspicuous feature of this portion. 



For purposes of study I have divided the arroyo into three 

 sections, the upper section being in the hills and watershed, the 

 middle section containing the portion bounded by the cultivated 

 mesa, and the lower section comprising the portion King in the 

 town and extending to the river. 



In the following lists I will include only those plants act- 

 ually collected or noted by the writer, and the lists given are 

 rather intended to show the range and character of the flora than 

 to be an absolutely complete census of its species, which might 

 prove too extensive for a paper of this sort. Some of the plants 

 noted occur in all of the course, but are listed in the section 

 where they are most commonly found. 



The plants of the upper section are such as are usually 

 found among the rocky foothills of the region, and are typical 

 of the Lower Sonoran Zone. The commonest species are as 

 follows: 



Dryopteris inunita Bromus Trinii 



Cheilanthes Cooperi Elymtis condensatus 

 Gyinnogramina triangularis Klymus glancns 



Notholaena Newberryi Rpicampes rigens 



Pellaea ornithopus Polypogon monspeliensis 



Pellaea andromedaefolia Stipa coronata 



Selaginella rupestris Stipa setigera 



Juniperus occiden talis Stipa speciosa 



