Opmilia. CACTACE/K. 249 



ivory-white seeds. — Nutt. in Torr. tt (Jray, Fl. i. 155. 0. erinacea, Engelm. & 

 Eig. Cact. 1. c. 47, t. 13, fig. 8-11. 



From the Mohave region (liiffc/ow) to Southern Utah {Pahnrr), and up tlie Colorailo Valley, 

 Nuttall. This plant seems to he Nuttall's long-lost 0. rnlila, and also 0. erinacea of the 

 Mohave, the flower of which is unknown. Joints 2 to 4 ineiies long, IJ to 3 wide, and often, 

 especially iu young plants, thick and almost terete, thus apjtroaching to 0. fragilis : seeds 3 

 lines wide. 



-»- -t- Joints a7id fruit 2}ubescent, ivithout spines. 



6. O. basilaris, Engelm. & Big. Low, with obovate often rctuso or fan-shaped 

 joints, ])nin(;liing only from the base : areolic very close, densely covered with short 

 brown bristles : flowers large, rose-purple : fruit subglo])ose, with deep umbilicus, 

 and rather few large and tliick seeds. — Cact. 1. c. 43, t. 13, Hg. 1 - 5. 



From the eastern base of the mountains near San Felipe through the desert and into Arizona, 

 Bitjelow, Newberry, Palvier, he. Joints 5 to 8 inches long, and often as wide near the top ; dis- 

 tinct from all other species of this region in its mode of growth, its pubescence, absence of spines 

 proper, and its very laige seeds (3J to 5 lines wide), which have a thicker but less prominent lim 

 than any other of this section. 



§ 2. Joints q/lindrical, more or less tuherculoted : rhaphe vsually not prominent, 

 therefore seed not margined : emhri/o forminrf less than one circle around the 

 more copious albumen ; cotyledons inconstant, contrary, oblique, or parallel to 

 the sides of the seed. — Cylindropuntia. 



* Low plants with clavate joints, rvithout a firm ligneous skeleton : larger spines 



angular-compressed, without sheaths : berries dry and very bristly. 



7. 0. Emoryi, Engelm. Joints long, clavato-eylindrical, with linear-oblong and 

 very ))rominent tuliercles : spines numerous (15 to 30) in the upper bundles, the 

 5 to 9 inner ones stouter, angular-compressed : seeds large, irregular, the rhaphe in- 

 distinct. — Cact. Mex. Bound. 53, t. 70, 71. 



Colorado deseit from San Felipe {Pnrrii, Birfr/ow) eastward, and into Arizona (Schott, Palmer) 

 and the Peninsuln, Gnhb. Joints 5 to 9 inches long, 1 to IJL thick; tubercles 1 to IJ inches 

 long ; fruit 2 to 2^ inches long ; seeds 2i to 3 lines wide. 



8. O. Parryi, Engelm. Joints short, ovate-clavate with oblong tubercles : spines 

 12 to 20, reddish gray, the 3 or 4 inner ones stouter, triangular-compressed : seeds 

 smaller, regularly circular, with a broad and disfinet rhaphe. — Am. Jour. Sci. 2 ser. 

 xiv. 339 ; Cact. of I'acif. U. l?ep. iv. 48, t. 22, lig. 4 - 7. 



Gravelly plains near the Mohavo IHver {Bhjelow), and through the desert to the base of the 

 mountains, Parry. Joints 3 or 4 inches long, 1^ thick ; tubercles aliout | incli long. 



9. O. pulchella, Engelm, Joints smaller, slender : tubercles small: spines 15 

 to 25, of which usually one only is stouter, flattened, deflexed : flowers purple : 

 ovary and fruit Avith long flexuous bristles : seeds small, with a broad rhaphe. — 

 Trans. Acad. St. Louis, ii. 201 ; Hot. King Exp. 119 ; fig. in Simpson TIep. ined. 



Sandy deserts of Southeastern Cnlifoniia and Nevada, and among the snge-bushes of the monn- 

 tnins, II. JCiKjchnnnn, ]V. (hihh, U'nhon. The juctlicMt and smiiilest i>i the clavate Opunliw, 

 the only one with purple (lowers ; joints rarely longer than 1 or 2 inches ; flowers l.{ lo 1^ inclics 

 wide ; seeds 2 lines in diameter. 



* * More or less erect, much branched : joints cylindric : ligneou,^ skeleton solid or 



tubular and reticulated : larger spines terete, coated irith a loose sheath. 



■¥- Fruit dry and spiny : flowers ycllou>. 



10. O. tessellata, Ejigelm. Much branched, bushy, from a stout ligneous 

 trunk : joints slender, covered with angular flattened ashy-gray tubercles, bearing 

 above long single loosely sheathed spines : flowers small, yellow : small oval fruit 

 covered with long brown bristles : seeds with a very broad flat rhaphe. — Cact. of 

 Pacif R. Rep. iv. 52, t. 21. 



