CACTACE, 51 
inch long, with a very deep umbilicus, and without any contraction at base; seeds 1.5-2.0 
lines in diameter, deeply notched at the hilum, very irregular. Distinguished from the nearly 
allied O. phceeacantha by its thinner joints, slenderer and longer spines, larger flowers, different 
fruit, &c. 
7. O. FILIPENDULA, (sp. nov.): adscendens, glauca; radicibus nodoso-incrassatis tuberiferis : 
articulis minoribus diversissimis orbiculatis seu obovatis seu oblanceolatis tenuibus ; foliis minu- 
tis subulatis ; pulvillis approximatis in tomento albo setas numerosas tenuissimas penicillatas 
demum elongatas virescenti-stramineas gerentibus, plurimis armatis seu omnibus plus minus 
inermibus ; aculeis 1-2 albidis elongatis setaceis non raro subangulatis tortisque, 1-2 minori- 
bus spe adjectis ; ovarii subcylindrici gracilis pulvillis 16-20 villo albo et setis parcis strami- 
neis munitis ; sepalis tubi sub-8 lanceolatis, interioribus obovato-cuspidatis ; petalis 8 late obo- 
vatis retusis purpurascentibus margine pallidioribus ; stylo purpurascente ; stigmatibus 5.erectis 
flavidis ; seminibus minoribus tumidis anguste crasseque marginatis. (Tab. LXVIII.) 
Alluvial bottoms of the Rio Grande, in rather fertile soil, near Dofia Ana, above El Paso, and 
at San Elizario, below it ; also on alluvial prairies between El Paso and the Limpia, Wright: 
fl. May and June.—The tubers of the root, $-1 inch thick, are long and cylindric, or oval, or 
globular swellings of the roots, strung upon thick fibres ; these tubers will sprout when planted. 
The stems are 6-12 inches high and spreading ; joints of a bluish glaucous hue, more so than 
any other of our species, very variable in shape, orbicular, or even transverse to obovate and 
lanceolate, often on the same plant, 14-3 inches long, 1~2 inches wide, very much compressed ; 
leaves 1}~-1} line long; pulvilli 4-6 lines apart, with a perfectly white tomentum, becoming 
grey when old, and numerous slender, greenish-yellow bristles, which finally become 2-8 lines 
long and very conspicuous. Sometimes the joints are entirely spineless, but usually they are 
armed with long, deflexed, very slender, white spines; the longer ones 1-2 inches, the lower 
and shorter ones less than 1 inch in length ; ovary slenderer than in any other species known 
to me, an inch long, at top hardly more than 3 lines wide; flowers about 24 inches in diameter, 
purplish, without any mixture of brick-red or yellow, as in the allied species. The only other 
purple one of our Platopuntic is O. basilaris, which is of a yet purer and deeper purple color. 
Fruit unknown ; seeds have been sent which have germinated and produced plants which already 
after the first year showed the characteristic glaucous hue and the tuberous roots. These seeds 
also differ from all our other Opuntia seeds by their great thickness, and their remarkably nar- 
row but thick and obtuse margin ; they are only very slightly notched at the hilum, and have 
a diameter of 1.7—2.0 lines, with a thickness of 1.2 lines. 
8. O. MAcRoruIzA, E. in Pl. Lindh., from between San Antonio and Austin, Lindheimer, is 
apparently well distinguished by its large tuberous roots, which even the young seedlings very 
soon begin to show ; but without these it is hardly distinguishable from O. Rajinesquii, E. 
of the Mississippi valley. I find the flower bud long-acuminate, and the stigmata always 5, 
(Tab. LXIX.) 
9. O. RUFIDA (sp. nov.) : erecto-patula ; articulis late obovatis seu suborbiculatis pubescenti- 
bus ; foliis e basi lata subulatis longe acuminatis ; pulvillis confertis griseo-villosis setas rufidas 
graciles numerosissimas penicillatas gerentibus inermibus; floris flavi ovario obovato pulvillis 
40-50 instructo ; sepalis tubi 20-30 exterioribus lineari-lanceolatis acuminatis, interioribus 
obovatis cuspidatis ; petalis (8?) orbiculato-obovatis obtusis erosis sepe mucronulatis ; stigmati- 
bus sub-7 abbreviatis in capitulum globosum congestis. 
* 
