Opuntia. CACTACEJE. 249 



ivory-white seeds. Nutt. in Torr. & Gray, Fl. i. 155. 0. erinacea, Engelm. & 

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



From the Mohave region (Bigelow) to Southern Utah (Palmer), and up the Colorado Valley, 

 Nwttall. This plant seems to be Nuttall's long-lost 0. rutila, and also 0. erinacea of the 

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

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

 lines wide. 



+- -i- Joints and fruit pubescent, without spines. 



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

 joints, brandling only from the base : areohe very close, densely covered with short 

 brown bristles : flowers large, rose-purple : fruit subglobose, with deep umbilicus, 

 and rather few large and thick seeds. Cact. 1. c. 43, t. 13, fig. 1 - 5. 



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

 Bii/c/mv, Neiubcrry, Palmer, &c. 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 large seeds (3J to 5 lines wide), which have a thicker but less prominent rim 

 than any other of this section. 



2. Joints cylindrical, more or less tuberculated : rhaphe usually not prominent, 

 therefore seed not margined : embryo forming 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, without a firm ligneous skeleton : larger spines 



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



7. O. Emoryi, Engelm. Joints long, clavate-cylindrical, with linear-oblong and 

 very prominent tubercles : 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 desert from San Felipe (Parry, Bigelow) eastward, and into Aiizona (Schott, Palmer) 

 and the Peninsula, Gabb. Joints 5 to 9 inches long, 1 to 1^ thick ; tubercles 1 to 1^ inches 

 long ; fruit 2 to 2^ inches long ; seeds 2^ 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 distinct rhaphe. Am. Jour. Sci. 2 ser. 

 xiv. 339 ; Cact. of Pacif. R. Rep. iv. 48, t. 22, fig. 4-7. 



Gravelly plains near the Mohave River (Biijrlow), and through the desert to the base of the 

 mountains, Parry. Joints 3 or 4 inches long, 1 thick ; tubercles about f inch 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 with long flexuous bristles : seeds small, with a broad rhaphe. 

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



Sandy deserts of Southeastern California and Nevada, and among the sage-bushes of the moun- 

 tains, H. Enrjclmann, W. Gabb, Watson. The prettiest and smallest of the clavate Opuntice, 

 the only one with purple flowers ; joints rarely longer than 1 or 2 inches ; flowers 1^ to 1^ inches 

 wide ; seeds 2 lines in diameter. 



* % More or less erect, much branched : joints cylindric : ligneous skeleton solid or 



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



+- Fruit dry and spiny : flowers yellow. 



10. O. tessellata, Engelm. 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. 



