San Joaquin Distriet. 613 
Rubus vitifolius C.& S.  Rhus diversiloba T. & G. 
Negundo californicum T.&G.(=Acer | Quercus Wislizeni D.C. 
egundo L. var. californicum | Cornus pubescens Nutt. (= C. occi- 
Sargent). | dentalis T. & G.). 
Oak Grove Formation. The bottomland nearer the foot hills is characterized by the 
presence of groves of Quercus agrifolia from three to eight feet in diameter which break 
the ee of the prairie-like levels. Prof. SARGENT, in his Silva, writes of this o 
valleys and low hills of the California coast owe their greatest charm to this oak ei; which, 
ie their covering of vernal green, or their brown summer surface with its low, broad heads 
of pale, contorted branches, and dense, dark foliage, gives them the appearance of incomparably 
beautiful parks 
Tule Marsh Formation. The course of the Sacramento River for a distance 
of 150 miles from its mouth is bounded by brackish marshes which stretch 
away from the river ten to fifteen miles on either side. These marshes are 
generally referred to as tule lands. Here Scirpus lacustris var. occidentalis 
chokes the marshland associated with Scirpus tatora forming thus almost pure 
associations covering extensive areas. 
The islands separated from each other by a labyrinth of tortuous channels are all of the 
same character, consisting of pure and exceedingly fine vegetal mold arising from the decay of 
tule and without trace of sand or gravel. They are all either entirely or in great part below water. 
- While the vegetation of the grassy Bo formation is brown in September and October, 
that of the river marshes is fresh and he color in these marshes in the autumn is 
dependent on the presence of Verbena ER Solidago occeidentalis, Aster Douglasii, Ra 
albens and Gnaphalium californicum. Annuals here are commonly four to six feet in height and 
plants eight to twelve inches high in dry soil here double their size, viz: Boisduvalia dh 
var. imbricata. Attention has already been called (see ante p. 2 to the fact that there is a 
strong resemblance between the flora of this formation and that of the low ground of the lower 
Mississippi River, but such plants as Lathyrus Jepsonii, Hibisceus ealifornicus, Bac- 
charis Douglasii are peculiar to California, while such herbs as Pluchea camphorata and 
Hypericum mutilum not only ocdur near the Mississippi, but in the salt marshes of the Atlantic 
coast as well. 
Sierra Nevadan District. 
This is coincident with the Sierra Nevada Mountains of California 
‚extending from the Klamath Gap (50 miles wide) south, as far as Tehachapi 
Pass which may be taken as the dividing line between the Sierra Nevada 
Mountains proper and the mountains of southern California, including the San 
Bernardino Range. — The Siskiyou Mountains and the Mt. Shasta Range 
may be said to form one division of the Sierra Nevada District and the moun- 
tains south of the Pitt River Gap (6o miles in width) between Mount Shasta 
and Mount Lassen another. 
a) Shasta Area. 
This area includes the mountainous country about Mount Shasta and the 
Siskiyou Mountains, which extend westward, until they blend with the Coast 
Mountains on the West. The effectiveness of the Klamath gap in actıng 
