Volume 5 August 5, 1909 



MUHLENBERGIA 



THE FLORA OF THE ARROYO TKRQUISQUITE 

 By Fred M. Rkki> 



Eastern and foreign botanists often remark upon the extent 

 and variability of our California flora, especially of this semi- 

 arid part, and even the portions considered to be really desert. 



Perhaps it will not prove uninteresting- to give the results 

 of a study of a small area in this so-called arid region. For some 

 years past I have been collecting and watching the changes in 

 the plant life of a near-by typical California arroyo locally 

 named the Arroyo Terquisquite, a name supposed to be of In- 

 dian origin, but no hint of its significance has been obtained 

 either from the earliest settlers or from the Indians themselves. 



This arroyo is simply a gully of erosion across the mesa 

 lying between the Box Springs mountains and the Santa Ana 

 river. Its branched heading in these hills is at an altitude of 

 about 1500 feet, and from these hills the arroyo takes its zigzag 

 way across the mesa with its level floor from fifty to eighty feet 

 below the surrounding mesa, and varying in width from a few 

 hundred feet to nearly half a mile, its walls for most of the 

 course being too steep for cultivation and broken by many gul- 

 lies running back into the level mesa land. The total length of 

 the area described is about four and a half miles. 



The hills at the upper end are of gray granite. About a 

 mile below the hills, the arroyo cuts through a dike of crvstal- 

 li/.ed calcite, and just above this dike are found outcroppings of 

 magnetic iron ore and a good quality of marble. With the ex- 

 < eption <>f the dike, the rocks of the arroyo consist of more or 

 less decomposed granite, in places replaced by a hard pan com- 

 posed of soil compacted by carbonate of lime. 



103) 



LIBRA 

 NEW Y 

 BOTANI 



(I a HtH 



