302 PLANTiE NOV^ THURBERIAN.^. 



Cereus,* which was afterwards met with more abundantly and of larger growth in 

 other parts of Sonera. The only flower seen was secured, and from it the de- 

 scription by Dr. Engelmann, in Silliman's Journal for May, 185-f, was taken. 



" Arispe, the terminus of the journey, is situated near the thirtieth parallel. Here 

 the pomegranate and fig attain great perfection, and here we first saw Opuntia Tuna 

 cultivated for its fruit. 



" A rapid return march was made to the Copper Mines, where our time was too 

 much occupied by preparations for a longer journey, to allow me to make many collec- 

 tions. In a visit to the pine woods near the mines, however, a new Potentilla with 

 blackish-purple flowers, Astragalus humistmtus, and a small Potato resembling Sola- 

 num tuberosum, were collected. 



"In August the expedition for the survey of the Gila left the Copper Mines to join 

 the Mexican Commission, then near the San Pedro River ; from which point a party 

 proceeded to the town of Santa Cruz. This section of the journey, especially the vi- 

 cinity of Santa Cruz, afforded a rich harvest of new plants, most of which have been 

 noticed in the publication of the collection of Mr. Charles Wright ; that excellent col- 

 lector having accompanied the expedition as far as to this point. 



" Santa Cruz is situated near the source of a small stream of the same name, in a 

 narrow valley, bounded by high and rounded hills, the ravines of which abound in in- 

 teresting plants. A new Perezia, not met with by Mr. Wright, was collected among 

 the hills ; and a curious MeJampodium Avas found on the margin of the river. 



" Failing to procure the provisions, in search of which Santa Cruz was visited, a 

 -small party, which I accompanied, proceeded to Ures, the present capital of Sonora, 

 taking the road by Magdalena, Cucurpe, Eayon, and other small towns. In a ca- 

 non near the deserted mission of Cocospera, Cereus gigantetis was first met with. The 

 first specimen brought the whole party to a halt. Standing alone upon a rocky pro- 

 jection, it rose in a single unbranched column to the height of some thirty feet, and 

 formed a sight which seemed almost worth the journey to behold. Advancing into the 

 canon, specimens became more numerous, until at length the whole vegetation was, in 

 places, made up of this and other Cactacete. Description can convey no adequate idea 

 of this singular vegetation, at once so grand and dreary. The Opuntia arborescens and 

 Cereus Thurberi, which had before been regarded with wonder, now seemed insignifi- 

 cant in comparison with the giant Cactus which towered far above them. In this 

 canon an old Texan acquaintance, Sesbania macrocarpa, was observed. Kosteletzkya 



* Cereus T/mrieri, Engelm. ; a species allied to C. giganteus, Engelm. — A. G. 



