STANDLEY— TREES AND SHRUBS OF MEXICO. 921 



Cespitose; stems procumbent, prostrate or ascending, decidedly narrowed 

 toward the tip, 10 to 22 cm. long, yellowish green ; ribs 8 to 10, rather low, not 

 at all sinuate, somewhat spiraled; spines 7 to 12, acicular, white with brown 

 or blackish tips; flowers 12 cm. long, rose-red to crimson, with an elongate 

 tube; perianth segments oblanceolate, acute. 



3. Echinocereus salm-dyckianus Scheer in Seem. Bot. Voy. Herald 291. 1856. 

 Ccreus salm-dyckiamis Hemsl. Biol. Centr. Amer. Bot. 1: 545. 1880. 

 Echinocerens salmianus Riimpler ; Forst. Handb. Cact. ed. 2. 809. 1885. 

 Cereus salmianus Weber, Diet. Hort. Bois 279. 1894. 



Chihuahua and Durango; type collected near tlie City of Chihuahua. 



Cespitose ; stems more or less decumbent, 2 to 4 cm. in diameter, elongate, 

 yellowish green ; ribs 7 to 9, low, more or less sinuate ; radial spines 8 or 9. 

 acicular, yellowish, about 1 cm. long; central spine solitary, porrect, a little 

 longer than the radlals; flowers orange-colored, 8 to 10 cm. long, narrow, the 

 tube elongate, the areoles of the flower tube and ovary bearing white bristly 

 spines and cobwebby hairs ; perianth segments oblanceolate to spatulate. 



4. Echinocereus huitcholensis (Weber) Giirke, Monatsschr. Kakteenk. 16: 



23. 1906. 



Cereus huitcholensis Weber, Bull. IMus. Hist. Nat. 10: 383. 1904. 



Known only from the type locality. Sierra de Nayarit, Jalisco. 



Plants 4 to 6 cm. in diameter ; radial spines 10 to 12 ; central spine usually 

 solitary ; flowers 11 cm. long, or less, narrow, with a pronounced tube ; color 

 of perianth segments uncertain but perhaps orange ; spines on ovary and tube 

 weak, acicular ; areoles of flower tube bearing long cobwebby hairs. 



5. Echinocereus pensilis (K. Brandeg.) Purpus, Monatsschr. Kakteenk. 18: 



5. 1908. 



Cereus pensilis K. Brandeg. Zoe 5: 192. 1904. 



Cape Region of Baja California, the type from Sierra de la Laguna. 



More or less cespitose, the stems often erect, 30 cm. high or when growing 

 on cliffs hanging and then nearly 2 meters long, 3 to 4 cm. in diameter ; ribs 

 S to 10, low; areoles about 10 mm. apart; spines needle-like, at first yellow, 

 becoming reddish gray, the longest not over 2 cm. long ; radial spines about 8 ; 

 central spine 1 ; flowers orange-red, narrow, 5 to 6 cm. long ; areoles on ovary 

 and tube bearing short, yellow or white wool and chestnut-colored bristly 

 spines ; fruit globular, 1.5 to 2 cm. in diameter ; seeds black, rugose, very 

 oblique at base. 



6. Echinocereus mojavensis (Engelm. & Bigel.) Riimpler; Forst. Handb. Cact. 



ed. 2. 803. 1885. 



Cereus mojavensis Engelm. & Bigel. Proc. Amer. Acad. 3: 281. 1856. 



Cereus higelovii Engelm. U. S. Rep. Miss. Pacif. 4: pi. 7/, i. 8. 1856. 



Reported from Sonora. Southwestern United States, the type from the 

 Mojave River, California. 



Cespitose, growing in massive clumps, often forming mounds, with hundreds 

 of stems (500 to 800 have been recorded) ; stems globose to oblong, 5 to 20 cm. 

 long, pale green ; ribs 8 to 13, 5 to 6 ram. high, but becoming indistinct on old 

 parts of stem, somewhat undulate ; areoles circular, about 1 cm. apart ; spines 

 all white, or in age gray ; radial spines about 10, acicular, spreading, curved, 

 1 to 2.5 cm. long ; central spine subulate, porrect or somewhat spreading, often 

 weak, 3 to 5 cm. long ; flowers rather narrow, 5 to 7 cm. long, crimson ; perianth 

 segments broad, obtuse or even retuse; areoles on ovary with white felt and 

 short acicular spines ; fruit oblong, 2.5 to 3 cm. long. 



