146 CACTACEAE 



more robust, less intricately branched; joints 10-25 cm. long; flowers and fruits larger. Borrego Valley, foot of 

 Mountain Springs Grade, Imperial County, California. 



5. Opuntia serpentina Engelm. San Diego Cholla. Fig. 3305. 



Cereus californicus Torr. & Gray, Fl. N. Amer. 1: 555. 1840. Not Opuntia californica Engelm. 1848. 



Opuntia serpentina Engelm. Amer. Journ. Sci. II. 14: 338. 1852. 



Opuntia californica Coville, Proc. Biol. Soc. Wash. 13: 119. 1899. 



Cylindr opuntia californica F. M. Knuth in Backeb. & Knuth, Kaktus-ABC 125. 1935. 



Prostrate-scrambling or low, ascending shrub with slender, cylindrical bluish green stems. 

 Joints 10-30 cm. long, 1.5-2.5 cm. in diameter, with somewhat flattened prominent tubercles 

 1-1.5 cm. long, slightly narrower than broad; areoles bearing 7-20 brownish acicular, rigid 

 spines 8-20 mm. long, yellowish brown felt and light brown glochids ; spines not interlocking nor 

 hiding the blue-green stems; flowers clustered at tips of branches, 2.5-3 cm. long (including the 

 ovary), about as broad when open, greenish yellow, the sepals and outer petals tinged with red; 

 fruit broadly ovoid, umbilicate at the apex, prominently tuberculate, spiny except at very base ; 

 seeds crowded in the fruit, angulate. 



Coastal foothills and mesas to 1,000 feet elevation, lower part of Upper Sonoran Zone; vicinity of San 

 Diego southward into Lower California about to Ensenada. April-May. 



6. Opuntia Bigelovii Engelm. Jumping or Ball Cholla. Fig. 3306. 



Opuntia Bigelovii Engelm. Proc. Amer. Acad. 3: 307. 1856. 



Cylindropuntia Bigelovii F. M. Knuth in Backeb. & Knuth, Kaktus-ABC 125. 1935. 



Sturdy erect plant usually with a central spiny trunk 7-10 cm. in diameter, 1-2.5 m. high, 

 and numerous short lateral branches, these soon deciduous below. Joints 5-20 cm. long, turgid, 

 with crowded tubercles and dense, closely interlocked armament, the terminal ones very easily 

 detached, primary ones persistent, turning sooty-black ; tubercles more or less 4-sided, 8-10 mm. 

 long, low; spines and sheaths shining pale yellow or roseate on young growth, 1.5-2.5 cm. long, 

 7-12 per areole, divergent; glochids and felt yellowish; flowers in clusters at the ends of joints, 

 greenish yellow, 2.5-4 cm. long, the petals rather few in number; ovary bearing areojes filled 

 with brown wool, glochids, and 1 to several small acicular spines 5-15 mm. long; fruit deeply 

 umbilicate, dry, greenish, nearly or quite spineless ; seeds flattened, angulate, greenish white, 

 seldom fertile. 



Forming extensive stands on dry hillsides, outwash slopes, mesas, and stabilized sand dunes, Lower 

 Sonoran Zone; southern Nevada to the western Colorado Desert, northern Sonora and east of the mountains in 

 northern Lower California. April. 



Opuntia Fosbergii C. B. Wolf, Occ. Papers Rancho Santa Ana Bot. Gard. 1:79. 1938. (Opuntia 

 Bigelovii var. Hoffmannii Fosberg, Bull. S. Calif. Acad. 32: 121. 1933, Opuntia Bigelovii X O. echinocarpa.) 

 Trunk vigorous, 2-3 m. high, often 2 to several branches from the base; shorter terminal joints more crowded 

 than in O. Bigelovii; tubercles essentially as in O. echinocarpa, twice as long as broad; the green stem showing 

 through armament; fruit as in O. Bigelovii. Mason Valley to Vallecitos, San Diego County, California. 



Opuntia Miinzii C. B. Wolf, Occ. Papers Rancho Santa Ana Bot. Gard. 1: 79. 1938. (Opuntia Bigelovii 

 X O. acanthocarpa.) Plant to 4 m. tall, with general h.ibit of X O. Fosbergii; tubercles narrower, 2-3 times as 

 long as broad; spines more slender and less crowded. Chocolate Mountains, Colorado Desert, California. 



7. Opuntia prolifera Engelm. Coast Cholla. Fig. 3307. 



Opuntia prolifera Engelm. Amer. Journ. Sci. II. 14: 338. 1852. 



Cylindropuntia prolifera F. M. Knuth in Backeb. & Knuth, Kaktus-ABC 126. 1935. 



Bushy or with a well-defined trunk 1-2.5 m. high, the trunk and older branches woody. 

 Joints 3-15 cm. long, 3-5 cm. in diameter, fleshy, turgid, easily detached, dark green; tubercles 

 short and usually low and inconspicuous ; areoles bearing yellowish brown felt, light yellow 

 glochids 1-2.5 mm. long, and 5-12 rusty to nearly black spines 8-25 mm. long, these more or less 

 divergently interlocked on young joints, sparser and fewer to lacking on older joints because of 

 weathering ; sheaths from sordid-yellow to rusty-brown ; flowers 1 to several at the ends of 

 branches, 2-3 cm. long (including the ovary) ; sepals green, tinged with rose; petals few, obovate, 

 obtuse, 5-8 mm. long, rose to rose-purple ; filaments greenish ; ovary tuberculate, the areoles 

 rather crowded, filled with light brownish glochids, the upper' containing also 1-5 ascending 

 acicular brown spines 5-18 mm. long; fruit globose, 2-3 cm. long, turgid, usually spineless, pro- 

 liferous, usually seedless ; seeds, when present, 5-6 mm. long, ovate, flattened. 



Arid hills and mesas, near the coast. Upper Sonoran Zone; Santa Rosa, Santa Catalina, San Clemente, 

 and Anacapa Islands, and vicinity of Ventura, California, southward into coastal Lower California to at least 

 Rosario; occasionally inland to limits of ancient beach. April-July. 



8. Opuntia Parishii Orcutt. Mat Cholla. Fig. 3308. 



opuntia Parryi Engelm. Pacif. R. Rep. 4: 48. pi. 22. figs. 4-7, pi. 24. fig. 7. 1856. Not O. Parryi Engielnv 



1852. 

 Opuntia Parishii Orcutt, West Amer. Sci. 10: 1. 1896. 

 Corynopitntia Parishii F. M. Knuth in Backeb. & Knuth, Kaktus-ABC 115. 1935. 



A low, creeping, matted plant rooting along the under surface, forming mats up to 1.5 m. 

 across, with erect, clavate branches 5-15 cm. high. Joints 2-3 cm. in diameter, nearly hidden by 

 the dense, interlocking spines; tubercles 5-10 mm. long, narrow, 3-6 mm. high, prominent; 

 areoles filled with white wool and yellowish glochids ; spines sheathless, reddish, fading to ashy, 

 the 3-4 centrals divergent, strongly flattened, subulate, 2-4 cm. long, the lowest broadest and 

 longest; radials 6-12, acicular, terete, spreading; sheaths early caducous; glochids numerous, 



