436 
EXPLORATIONS ACROSS THE GREAT BASIN OF UTAH. 
crowded at the end of lateral branchlets, a few lines to 1 or 1J 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 1,-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 J line in diameter. Immediately after flowering, the silky-featherv 
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 somewhat 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 year’s growth 
at the end of each branchlet; they probably fall off when about 15 or 18 months old. 
This fine tree, discovered by Nuttall -on Bear River, north of the Salt Lake, and 
hear Thomberg’s Ravine” in the Rocky Mountains, was found by the expedition on 
the Lookout Mountains and other mountain-chains of the basin. 
CACTACEiE. 
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 
Cereus, and 4 Opuntise. Several species known before have been found in new local¬ 
ities, and 3 new and very distinct species have been discovered, 2 Echinocacti and 1 
Opuntia. 
Mamillaria vivipara, Haworth, Suppl. p. 72; Torrey & Gray, FI. N. Am. 2 p 
554; Engelm. Synops. Gact. p. 13; Cactus viviparus, Nuttall, Gen. 1 ,p. 295. 
Was collected in the South Pass and on Sweetwater River. It extends from her< 
to the mountains of Colorado and New Mexico, but its most characteristic forms an 
peculiar to the more elevated plains, where it assumes that cespitose, spreading appear¬ 
ance, from which it has received its name. The mountain form usually makes largei 
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 from allied species. 
Botanical 
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