14 BOTANY. 



the wild oat. These plants give the gay and varied appearance to the botany of the region, 

 which has been remarked by all who have visited it at the proper season. 



In the valleys of Napa and Sonoma the climate is intermediate in character between that of 

 the coast and the interior, the extremes of each being tempered to produce a mean in the highest 

 degree healthful, agreeable, and favorable to the development of vegetation. Here we find, 

 besides a great profusion of annual plants, the California white oak, (Q. Hindsii,) which grows 

 solitary or grouped in the manner of the evergreen oak, but attaining a much greater size. 

 Here also, for the first time, we met with the nut pine, (P. sabiniana,) a tree highly character- 

 istic of the flora of the interior, and generally distributed through the coast mountains back from 

 the ocean. The Nanzanita and several species of CeanotJius form shrubby clumps and thickets. 

 Here, as elsewhere in this region, the lupins, one of which (L. macrocarpus) is shrubby, form a 

 marked feature in the vegetation. About Benicia, the rounded hills are everywhere covered 

 with wild oats, and no trees are visible except the evergreen oak, which forms low and limited 

 groves in the ravines among the hills and on the slopes of Mount Diablo. The shores of 

 Suisun bay, as well as the borders of the lower Sacramento and San Joaquin rivers, exhibit 

 wide expanses of tule, (Scirpus lacustris,) which forms in its abundance a striking peculiarity of 

 the botany of all portions which we visited of California and Oregon. The reasons for the 

 prevalence of this plant are, however, probably to be found in the imperfect drainage of much 

 of the surface, rather than in any peculiarities of soil or climate. The low lands bordering the 

 belt of tule which encircles Suisun bay, are in many places covered and reddened by the Can- 

 chalagua (Eryihrea Mulilenhergii.) The botany of Suisun valley exhibits many of the charac- 

 teristics of that of the valleys of Napa and Sonoma. The soil, which is, for the most part, 

 derived from the decomposition of sandstone rock, was originally covered with the wild oat, 

 which here grows in great luxuriance, and with beautiful trees of the Californian white oak, 

 (Quercus Hindsii.) A large part of the surface is now under cultivation, and at the time we 

 traversed it was covered with wheat just ready for the reaper. It exhibited a vigorous growth, 

 and, as I was informed by the farmers, produced from 25 to 50 bushels to the acre ; the yield 

 being greatly affected by the degree in which the great want of the region, that of water, was 

 supplied. 



At Vacaville we left the foothills of the coast "mountains, traversing the valley of the Sacra- 

 mento diagonally to the foot hills of the Sierra Nevada, near the upper end of the valley. The 

 rolling surface of the foot hills, on either side of the Sacramento, is covered with wild oat, 

 scattered trees of the oaks I have mentioned, and, in the more rocky places, 'the nut pine. The 

 plain bordering the river exhibits surfaces of different characters, and covered with differing 

 vegetation. The upper terrace is frequently gravelly, and sustains a sparse growth of coarse 

 grasses, of Eryngium, Heraizonia, Madaria, and other rough or viscous plants ; such surfaces 

 being comparatively sterile and of little value for cultivation. The alluvial plain immediately 

 bordering the river possesses a fine and fertile soil, and is covered with a dense growth of wild 

 oat, Artemisia, and other plants. The banks of the streams are lined with belts, of greater or 

 less width, of timber, which are composed chiefly of the long-acorned oak, (Q. Hindsii,) here 

 exhibiting a size and beauty of form not surpassed, if equalled, by the oaks of any other part of 

 the world. Along the water's edge, the sycamore, (P. liacemosa,) Fraxinus Oregona, the 

 cotton-wood, (P. 3Ionili/era,) and two species of salix, (S. Hindsiana and S. lasiandra ?,) are 

 overgrown by grape vines, {Vitis Cali/ornica,) and form a screen, by which the view of the 

 river is frequently shut out from the traveller upon its banks. At the north end of the valley, 



