436 EXPLORATIONS ACROSS THE GREAT BASIN OF UTAH. 



crowded at the end of lateral branchlets, a few lines to 1 or 1 J inches in length closely 

 covered with circular scars. Leaves very thick and leathery, persistent, lanceolate, 

 acute at both ends, entire and revolute at the margin, with a thick midrib, prominent 

 on the lower surface, 9-14 lines long, 2J-3J lines wide, on a petiole 1 J-2 lines long, 

 to the lower part of which adhere lanceolate, brown, scarious stipules. When young, the 

 branchlets as well as the leaves are covered all over with short, curly hair; when older, 

 the leaves become glabrous and glossy on the upper surface, the lower remaining hairy 

 and assuming a rusty color. The sessile flowers are produced in June from the 

 axils of the uppermost leaves of the preceding year's growth, either single or 2 or 3 

 together; short scarious bracts envelop the base of the cylindrical woolly calyx-tube, 

 which is 3 lines long; its 5-lobed, white limb, 3-4 lines in diameter, is very woolly 

 externally, and less so internally, and bears about 20 or 25 naked, slender filaments^ 

 with reniform anthers I line in diameter. Immediately after flowering, the silky-feathery 

 style becomes elongated, and carries up with it the detached limb of the calyx; at 

 maturity, the style becomes a twisted, feathery tail of about 2 inches in length; the 

 inconspicuous, linear, hairy fruit itself is about 4 lines long, and remains hid in the 

 persistent, calyx-tube; at its top and base I observe a beard of very curious, stiff, white 

 bristles, less than a line in length, thicker in the middle, and tapering toward both ex- 

 tremities. The fruit seems to be somewhal persistent, as I find it in specimens collected • 

 in spring before the flowering-season. About the time of flowering, the young leaves 

 begin to develop at the end of the branchlets, leaving the flowers between them and 

 the leaves of the year before. I generally find 4 or 5 leaves of the same years growth 

 at the end of each branchlet; they probably fall off when about 15 or l.S months old. 

 This fine tree, discovered by Nuttall on Bear River, north of the Salt Lake, and 

 near "Thornberg's Ravine" in the Rocky Mountains, was found Uy the expedition on 

 the Lookout Mountains and other mountain-chains of the basin. 



CACTACE.E. 



The geographical limits of the area of this curious American family have been 

 considerably enlarged by this expedition, proving the presence of at least 7 species in 

 the Utah Basin between the thirty-eighth and fortieth parallels, viz: 2 Echinocacti, 1 



Opuntia. 



Mamillakia vivipara, Haworth, Suppl. p. 72; Torrey & Girt//, Fl N. Am 2, p. 



554; Euf/r/m. Synops. Cad. j>. 13; Cactus viviparus, Xntfafl, Gen. \, p. 295. 



Was collected in {he South Pass and on Sweetwater River. It extends from here 

 to the mountains of Colorado and New Mexico, but its most characteristic forms are 



peculiar to the more elevated plains, where it assumes that cespitose, spreading appcar- 



heads, but remains single or branches out very sparingly. Its large purple flowers, 

 with numerous lance-linear, long acuminate, bristle-pointed petals, and its leather- 

 brown pitted seeds, readily distinguish it iron, allied species. 



