930 CONTEIBUTIONS FEOM THE NATIONAL HEEBAEIUM. 



44. Echinocereus stramineus (Engelm.) Rumpler ; Forst. Handb. Cact. ed. 2. 

 797. 1885. 



Cereus stramineus Engelm. Proc. Amer. Acad. 3: 282. 1856. 



Chihuahua. Western Texas and southern New Mexico ; type from El Paso. 



Plants grouped in masses forming immense mounds 1 to 2 meters in di- 

 ameter and 30 to 100 cm. high ; joints 12 to 25 cm. long, 3 to 7 cm. in 

 diameter ; ribs about 13, almost hidden by the long spines ; spines at first 

 brownish to straw-colored, in age nearly white ; radial spines 7 to 14, 2 

 to 3 cm. long, spreading ; central spines 3 or 4, 5 to 9 cm. long ; flowei's 

 purple, 8 to 12 cm. long; perianth segments oblong, 3 to 4 cm. long, rounded 

 at apex ; spines from the axils of scales on ovary and flower tube, 2 to 5, 

 short, white; fruit nearly globular, 3 to°4 cm. in diameter, red, spiny at first, 

 becoming glabrous, edible; seeds 1.5 mm. in diameter, somewhat oblique. 

 " Pitahaya." 



45. Echinocereus barthelowanus Britt. & Rose, Cactaceae 3: 41. 1922. 

 Type from Santa Maria Bay, Baja California. 



Plants cespitose, forming large clusters ; stems cylindric, 10 to 20 cm. 

 long, 4 to 5 cm. in diameter ; ribs about 10, somewhat tuberculate below, but 

 completely hidden by the stout numerous spines ; areoles 2 to 5 mm. apart, 

 white-felted when young; spines numerous, acicular, sometimes 7 cm. long, 

 pinkish when quite young, afterwards white or yellow with brown or blackish 

 tips, in age becoming gray ; flowers only 10 to 12 mm. long ; perianth seg- 

 ments oblong, 3 to 4 mm. long; ovary minute, strongly tubercled, hidden 

 under the mass of spines; spine clusters on ovary with 6 to 12 white op 

 pinkish-tipped spines, half as long as the flower, 



46. Echinocereus mamillatus (Engelm.) Britt. & Rose, Cactaceae 3: 41. 1922. 

 Cereus mamiUatnx Enjiehn. : Coulter. Contr. U. S. Nat. Herb. 3: 405. 1896. 

 Southern Baja California; type from Muleg6. 



Cespito-se; stems ascending, 20 to 30 cm. long, cylindric, 3.5 to 6 cm. in 

 diameter; ribs 20 to 25, sometimes oblique, strongly tuberculate; spines 

 white or pinkish; radial spines 10 to 25, acicular, 3 to 12 mm. long; central 

 spines 3 or 4, much stouter than the radlals, 1 to 2.5 cm. long. 



This and the following species are omitted from the key because their 

 characters are still imperfectly known. 



47. Echinocereus ehrenbergii (Pfeiff.) Riimpler; Forst. Handb. Cact. ed. 2. 

 775. 1885. 



Cereus ehrenbergii Pfeiff. Allg. Gartenz. 8: 282. 1840. 



Central Mexico. 



Cespitose, 20 cm. high; joints often procumbent, pale or leaf-green; ribs 

 6, obtuse, sinuate; areoles 2 cm. apart, white-felted; radial spines 8 to 10, 

 slender, white ; central spines 3 or 4, yellowish at base. 



48. Echinocereus longisetus (Engelm.) Rumpler; Forst. Handb. Cact. ed. 

 2. 822. 1885. 



Cereus lougisetus Engelm. Proc. -Amer. Acad. 3: 280. 1856. 



Coahuila; type from Santa Rosa. 



Plants simple or nearly so, cylindric, 15 to 25 cm. long, 5 to 7.5 cm. in 

 diameter ; ribs 11 to 14, somewhat tubercled ; areoles circular ; spines slender, 

 elongate, white ; radial spines 18 to 20, spreading, the lower 10 to 15 mm. long, 

 much longer than the upper; central spines 5 to 7, very unequal, the lower 

 elongate, 2.5 to 5.5 cm. long, deflexed ; flowers said to be red. 



