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UNITED STATES AND MEXICAN BOUNDAEY. 



"wlien green. In this locality are also found tlie beautiful Ceanothus rigidus^ Pitavia dumosa^ 

 ^Adenosiomafascicu^afa^ and a species of scrub oak, all forming dense thickets. 



We must not omit to mention the Caciacewy which here present species of all the extra 

 tropical genera, as remarked by Dr. Engelmann in his memoir upon this family. These plants^ 

 from their striking and singular forms, impart a characteristic feature to the region they inhabit. 



A new species of pine is peculiar to the district now under consideration. It occupies an arid 

 tract near the ocean beach^ about twelve miles north of San Diego^ at the entrance to Solidad 

 valley. In this locality (the only one in which it has been found) it forms a small sized tree, 

 witli rather open foliage. It is particularly distinguished by its long fascicles of leaves, which 

 are in fives, and its large ponderous cones. This species, the specific characters of which will be 

 found more fully described in the following list, I have ventured to designate, in compliment to 



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a disfinguished American botanist, as Pinus Torreyana. 



Along the borders of the streams which traverse this Supra-Littoral district are found the 

 common cotton-wood, {Pojpulus angustata^ the Plat anus 3IexicanuSy and, in the lower portion of 

 the San Luis Eey valley, an Alnus ; these, with various species of willow, make up the proper 

 timber growth of this region. The undergrowth in these localities consists mainly of coarse 

 representatives of the order GompositcBy conspicuous among which are several shrubby species of 

 BaccJiaris. In moist places Anemiojosis Cali/ornica is frequently met with, and where the soil is 

 rich the surface is covered by a rank growth of wild mustard {Sinapis nigra) and mallows^ 

 (llalva ohiusa,) 



The herbaceous and annual plants of this region are so numerous that we can only allude to 

 a few of the more striking and characteristic. 



It is in the latter part of winter and during the earlier spring months that California puts on 



lier richest floral garb. Then the arid hills assun 

 summer appearance. In February the moistened 

 varied tints. The pale blossom of the eles:ant Do 



different from their d 



ifoli 



borhood of Los Angeles are covered with the richest pasturage. The Erodium cicutarivm.y 

 (called here '^pin grass,'' and furnishing a highly esteemed fodder,) with several species of wild 

 clover, {Trifolium and MedicagOy) are mingled with a variety of other herbage, and thus serve to 

 give a meadow-like aspect to this teeming land- Such is the general appearance of the country 

 from February to April, inclusive, and then is to be seen the glory of the Californian flora* 



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blue Lupines and rainbow colored Gilias deck the ground, and various ferns and mosses appear, m 



The Piihes speciosum hangs its scarlet pendants, and the rich yellow flowers of Viola pedunculata 



are abundant everywhere. Even the numerous northern genus Saxifraga is represented here 



by more than one species. A large number of ffydropJiyUacece^ including species of Nemophila^ 



Pliacelia^ and Eufoca, are among the early tokens of spring, while the orange colored flowers of 



Escholtzia, the pale blooms of Plafystevion, and the pink ones of Meconopsis^ show that the 



poppy family contribute largely to make up the vernal flora. Among the twiners are a species 



of Clematis that is either new or a variety of G. jpaudjlora and Megarrhiza CaUfornica of Torrey ; 



the latter plant_, which hangs its prickly burs from almost every bush, is remarkable for the ^ 



enormous size of its root. Further to the north the valleys arc clothed with a luxuriant growth ^ 



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of wild oatS; (Avena fatua,) which is so extensively naturalized that it gives to every fertile 

 tract the appearance of a cultivated field. The wide plains that border the sea in the neigh- 



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