214 CACTACEH OF THE BOUNDARY. 
uth range of the Sierra Babuquibari, in Sonora, and southeastward, in fertile valleys (Schott). Flowers in 
July and August. — This peculiar species is more tree-like than any other Sonorian Opuntia. It has a distinct trunk 
and a dense top, much like any other ordinary tree, though only 5 or 6 feet high ; the joints are 3 or 4 inches long 
and 1} inch in diameter ; the swelling tubercles much resemble those of a Mamillaria, whence the name ; the thick 
leaves are scarcely a line long; spines few, 3-9 lines long, sometimes almost wanting. The flowers are hardly an inch 
in diameter, and of a bright pink or purple color; the ovary is 8 or 9 lines long, and the fruit of the same length, 
slightly tuberculate, in all the specimens before me unarmed (according to Mr, Schott’s notes, “ spiny”). Seeds 
1-1} line in each dimension, often higher than broad, very irregular, remarkably similar to those of 0. fulgida,.but 
scarcely beaked, and still more compressed ; cotyledons incumbent.or often somewhat oblique 
24, O. THURBERI, sp. nov.: frutescens, erecta; articulis cylindricis gracilioribus tuberculatis; tuberculis 
oblongo-linearibus minus pevieatinalin': pulvillis iTbvcabiodtatin breviter fulvo-tomentosis vix setosis ; eis 3-5 
brevibus obscuris stramineo-sen fulvo-vaginatis lateraliter divergentibus, infimo robustiore deflexo; flore miniato ; 
ovarii clavati tuberculati pulvillis 18-20 tomentosis brevissime setosis et parce aculeolatis ; nena tubi cbovetis 
eget petalis erectiusculis obovato-spathulatis obtusis retusisve ; stigmatibus 7 brevibus crassis erectis. 
cuachi, Sonora (G. Thurber). owers in June. = Bele; in some respects to O. arborescens ; but the 
slender poria only about 6 lines in diameter; tubercles 9 lines long; spines 3-8 lines long, the lowest one the stoutest ! 
and deflexed. The ovary is about 10 lines long, and bears on some - the pulvilli 1 or 2 spines, which are evidently 
deciduous, as we see them in O. arborescens and 0. Whipplet. The flower is 1} inch in diameter, dull brick-red, salver- 
form, and opens much less than that of O. arborescens, which j is pure purple ; porte 1-1} line long. 
This species I have named for its discoverer, Mr. George Thurber, who, in . Commissioner Bartlett’s party, 
traversed Sonora, and gathered many interesting plants in that then almost unknown country. 
25. O. Wricurt, sp. nov.: caule frutescente erecto, juniore reticulate, seniore compacto-lignoso ; ramis 
adscendentibus ; articulis cylindricis gracilibus sub-tuberculatis ; tuberculis elongatis depressis ; foliis elongatis 
subulatis patulis ; pulvillis orbiculatis albo-tomentosis setas gracillimas scakalina gerentibus ; aculeis singulis (seu 
rarius wha superioribus minoribus adjectis) porrectis seu paulo deflexis e cinereo rubellis vagina straminea decidua 
indusiatis ; flore miniato; ovarii obovati pulvillis 15-18 albo-tomentosis setosisque ; sepalis tubi 9-12 orbiculatis, 
samen cuspidatis, interioribus obtusis ; petalis sub-8 late obovatis emarginatis ; styli crassi stigmatibus 6-7 
brevibus adpress 
Common on steep rocky mountain-sides on the Limpia (Wright), and along the Rio Grande from Presidio del 
Norte to the Pecos (Parry, Bigelow) ; also — in Mexico (Gregg). Flowers in June and July. — A shrub, 
2-4 feet high, about 1 or 1} inch thick below, intermediate between O. arborescens and O. frutescens in size, structure of 
stem, and arrangement of spines. Branches few ; va 4 lines in diameter; tubercles flat, 7-9 lines long; leaves 
about 5 lines long. Spines 8~10 lines in length, generally single or with 1 or 2 small and divergent ones above ; in 
one specimen before me those upper spines are almost as stout and long as the lower one. Flowers about 1 or 1} inch 
in diameter ; ovary 7-8 lines long. Fruit unknown. 
This pretty species of Opuntia bears a name which has been often mentioned in these pages, and which is [60] 
forever inseparably connected with the botany of our Southern boundary. 
6. O. ARBUSCULA, sp. nov. : caule erecto arborescente dense lignoso apice ramosissimo capitato ; ramis divari- 
catis elongatis — snhacubiie: articulis junioribus lete viridibus leviter tuberculatis ; tibetealis oblongo- 
linearibus depressis ; pulvillis magnis orbiculatis albo-tomentosis; setis parcis gracillimis penicillatis aculeis singulis 
(seu subinde binis Interalibus) porrectis demum deflexis stramineo-seu fulvo-vaginatis, rarius une alterove breviore 
inferiore deflexo adjecto; flore flavo-virescente ; ovarii clavati pulvillis 16-18 albo-tomentosis vix setosis; sepalis tubi 
sub-8 orbiculatis cuspidatis seu mucronatis ; petalis sub-5 spathulatis, staminibus extus in staminodia latiora subulata 
transeuntibus; stigmatibus 5 brevibus erectis. 
n the desert heights, near Maricopa village, on the Gila (Schott), Flowers in June. — A truly arborescent 
species, 7-8 feet high, with a solid ligneous trunk, 4-5 inches thick, smooth green bark, and a top formed by the 
numerous slender and divaricate branches; ultimate joints 2-3 inches long, renee 4 lines in diameter ; tubercles flat 
and indistinct, about 6 lines long; spine 9-12 lines long. Ovary, in my specimen, 10 lines long and only 4 lines in 
” 
Flower apparently nearly 1} inch in - diameter ; petals few, 9 lines long and 4 lines broad, greenish-yellow, tinged 
with red. Stamina and staminodia (perhaps what I consider so are but the broader filaments of the exterior fertile 
stamens) finally breaking off near their base, leaving a rough surface. The name of this species indicates a small tree. 
27. O. rRurEscens, E. in Plant. Lindh., was collected abundantly in all western Texas and southern New 
Mexico, For a fuller account and a figure, see Engelmann and Bigelow’s paper on the Cactacew of Captain Whipple’s 
Pacific Railroad Exploring Expedition Report. 
