248 CACTACE^E. Opuntia. 



§ 1. Joints compressed : rhaphe forming a prominent bony margin around the seed : 

 embryo completing a little moi'e than one circle around the scanty albumen; 

 cotyledons contrary to the sides of the seed. — Platopuntia. 



* Fruit pulpy. 



1. O. Engelmanni, Salm. Bushy, erect-spreading, much branched : obovatc 

 joints i to 1 foot long, sparsely armed with bundles of 1 to 3 or sometimes even 5 

 spines, the stouter ones angled, yellow, sometimes with a red-brown base; old trunks 

 losing their spines : flowers yellow, about 3 inches wide : petals broadly obovate, 

 truncate : the purple oval juicy berry about 2 inches long, with a large flat um- 

 bilicus, and with 20 to 25 brown-woolly and slightly bristly areola;. — Salm. Cact. 

 cult. 1S49, 235 ; Engelm. Cact. Mex. Bound. 47, t. 75, fig. 1-4. 



Var. 0. occidentalis, Engelm. Spines fewer, stouter, farther apart : seeds 

 larger. — 0. occidentalis, Engelm. &, Big. in Cact. of Pacif. B. Eep. iv. 38, t. 7. 



Var. (1) y. littoralis, Engelm. Joints often larger, 1 to 1 \ feet long: bunches 

 of longer and more slender spines closer together : fruit similar, but with 40 to 50 

 areolae : seeds smaller. 



Apparently a polymorphous species, extending from Southern Texas to the Pacific, which will 

 probably be identified with some older Mexican species when these plants come to be better 

 understood. The two forms of California are easily distinguished by the characters given above. 

 The var. occidentalis has been found on the western slope of the mountains east of Los Angeles 

 and southward to San Isabel, etc., at an elevation of 1,000 to 2,000 feet, Parry, Scholt. The 

 areolaj of the joints are 1J to 2 inches apart ; spines 4 to 1J inches long ; flowers 3 to 3i_ inches 

 wide, yellow with orange centre; fruit often 1-?,- inches thick; seeds 2i to 2| lines wide. The 

 second form, var. littoralis, extends on the coast from Santa Barbara and the islands in its gulf 

 (O. Tittmann) to San Diego, and southward, G. N. Hitchcock. Seeds 2 to 2J lines in diameter. 



— The limits of these species are difficult to circumscribe, especially because complete speci- 

 mens are so hard to preserve and extensive observations in the field have not yet been made. Of 

 the three following no more is known now than there was twenty years ago. 



2. O. chlorotica, Engelm. & Big. Erect, busby ; old trunks covered with 

 large areolae which, retaining their vitality, constantly produce new spines ; joints 

 large, pale green, orbicular-obovate, with close-set areohe, each bearing 1 to 5 slender 

 deflexed yellow spines : flowers yellow, 2J to 3 inches wide, with spatulate petals. 



— Cact. of Pacif. E. Eep. iv. 38, t. 6, fig. 1 - 3. 



From Mohave Creek eastward to Bill Williams Mountain in Arizona (Bigelmv) ; 4, 5, or even 7 

 feet high, readily recognized by the very spiny trunk and very pale broad joints | to 1 foot long. 



3. O. angustata, Engelm. & Big. Prostrate or ascending, witli obovate elon- 

 gated joints : large oblong areolae sparse, bearing brown bristles and few (1 to 3) 

 deflexed spines : fruit rather small, deeply ivmbilicate, with few large seeds. — Cact. 

 1. c. 39, t. 7, fig. 3, 4. 



From Cajon Pass eastward into Arizona, Bigelmv. Joints 10 inches long or more, not half as 

 wide above, narrowed downward ; berry 1A_ inches long, narrow; seeds 3 lines wide. 



4. O. Mohavensis, Engelm. & Big. Prostrate, with large nearly orbicular 

 joints, and more numerous (2 to 6) stout and long often curved brown spines. — 

 Cact. 1. c. 40, t. 9, fig. 6-8. 



On Mohave Creek, Bigelmv. A doubtful form, of which Dowel's and fruit are unknown. It 

 seems to approach 0. phecacantha of New Mexico, and perhaps even the stouter western forms 

 of O. Rafinesquii. It is indicated here merely for the attention of future explorers. 



O. Tuna and O. Ficus-Indica, Mill., are probably both naturalized about the old missions ; 

 one with stout yellow spines and insipid fruit, the last with weaker whitish spines, fruit delicious. 



-t- Fruit dry. 



+-i- Joints and fruit spiny. 



5. O. rutila, Nutt. Prostrate, with thick obovate or elongated joints : areole 

 close, armed with numerous slender reddish or gray flexible spines : large flowers 

 purple : stigmas green : berry deeply umbilicate, with large flat broadly margined 



