INTRODUCTION. 



21 



tinct. It lias a very compact, symmetrical form. The young individuals present a regularly 



con 



Older plants attain a height of from 25 to 40 feet, and show a short trunk which supports a 

 rounded head. This species hears an edihle nut, which iwS colk^cted hy (he Indians as an article 

 of food. 



Besides the pines, the other Coni/enc are Abies Douglasii and TJiuJa occidenfalis. 



We always find upland oahs a?sociated with the pine growth of this region. These include 

 the common Quercus agrifolia and Q. densijlora^ the latter species heing the more common upon 

 the higher ridges. It is of stochy habit, and has wide-spreading hranches, which form large 

 spherical heads. Tlie hark of this tree appears like that of the elm, and tlie wood is close- 

 grained and durahlo. 



There is another oak, which has deciduous leaves, the two preceding heing ever<^reens. It 

 seems to he closely allied to or identical with Q. tinctorxa. Of this species there arc two varie- 

 ties which are only distinguishable by the fruit, which in one has a large and prominent 

 gland, while in the other the gland is almost concealed by the cup — characters which seem to be 

 constant in the same individuals. 



The shrubbery of this region presents but little variety, and consists mostly of species which 

 have been enumerated as belonging to the Lovrcr Mountain district. 



0*"'0 



We naturally expect to find here the undergrowth which, in all countries, accompanies the 



pine forest. Here 



3 to 



[Fragaria vesca^) 



Cyclohoth 



species of Bentham. But of Orcliidacece^^o Qomm^ou elsewhere in such localities, we have only 

 a solitary species of Plaianthera. Curices are sparsely distributed, and PotentiUa^ so common 

 in northern latitudes^ has a place in our catalogue. The well-watered valleys are covered with 

 a fine sward of native grasses, and lichens of sparkling yellow decorate the decaying pines. 



VEGETATION OP THE EASTERN SLOPE OF THE MOUNTAINS, THE DESEET, K^D THE BASIN OF THE COLORADO. 



The features which vegetation presents, within the limits of this section, may be best de- 



scribed by noticing those which would naturally attract the attention of the traveller. The 



vegetation of the summit ridge differs hut little upon its eastern and western side ; but as we 



go further down the abrupt eastern descent a new group of plants comes into view, one which 



p presents a marked contrast to that occupying the corresponding Lower Mountain region of the 



Pacific side. Here thorny shrubs and stiff-stalked plants of strange aspect meet the eye. The 

 ashen colored mountains, which in the distance seem entirely destitute of vegetation, produce in 

 their rocky canons and crevices a great variety of singular forms. Cacti again appear, and, 

 excej>t in one or two instances, are all different from those found on the Pacific 8lo2)e. There 

 are several Opuntias^ both those with cylindrical and those with elliptical stems. The gigantic 



Echino 



mamillaries are also met with. A new spe 



ties, and bears a deliciously palatable fruit. 



On the unland i^Uina nno^ ^'u^ ^;i«.^ ^^^-i 



of the rock, and the humbler 



((7. Engelm 



foliage and trumpet-sbaped flowers. This sliowj plant is Chilopsis linearis. Here 



K. 





