924 CONTRIBUTIONS FEOM THE NATIONAL HERBAEIUM. 



Plants usually simple, cylindric, 10 to 30 cm. high, very spiny; ribs 15 to 

 21, 2 to 3 cm. high; areoles 3 to 5 mm. apart, short-elliptic; radial spines 16 

 to 24, more or less spreading, 1.5 cm. long or less, at first pinkish but gray in 

 age; central spines 3 to 8, a little stouter than the radials, never in a single 

 row; flowers from near the apex, often 10 cm. long, yellowish, or drying red- 

 dish ; outer perianth segments linear-oblong, 4 to 5 cm. long, acute, inner ones 

 oblong, 5 cm. long; ovary very spiny; fruit nearly globular, 2.5 to 3.5 cm. in 

 diameter, purplish, edible. 



18. Echinocereus ctenoides (Engelm.) Riimpler; Forst. Handb. Cact. ed. 2. 

 819. 1885. 



Cereus ctenoides Engelm. Proc. Amer. Acad. 3: 279. 1856. 



Chihuahua. Texas, the type from Eagle Pass. 



So far as known simple, cylindric, elongate, 10 to 40 cm. long, 8 to 10 cm. 

 in diameter, decidedly banded with pink and gray as in the rainbow cactus; 

 ribs 15 to 17, low ; areoles crowded together, short-elliptic ; radial spines often 

 as many as 20, not spreading but standing out at an angle to the ribs; central 

 spines 8 to 10, arranged in a single row or sometimes a little irregular ; flowers 

 up to 10 cm. long, about as wide as long when fully expanded, bright to red- 

 dish yellow ; ovary and fruit very spinJ^ 



19. Echinocereus blanckii (Poselger) Palmer, Rev. Hort. 36: 92. 1865. 

 Cereus blanckii Poselger, Allg. Gartenz. 21: 134. 1853. 



Cereus berlandieri Engelm. Proc. Amer. Acad. 3: 286. 1856. 



Echinocereus poselgeriamis Linke, Allg. Gartenz. 25: 2.39. 1857. 



Echinocereus leonensis Mathsson, Monatsschr. Kakteenk. 1: 66. 1891. 



Northeastern Mexico; type from Camargo, Tamaulipas. Southern Texas. 



Procumbent; joints slender, 3 to 15 cm. long, 2 to 2.5 cm. in diameter; 

 ribs 5 to 7, strongly tuberculate, or when turgid scarcely tubercled; areoles 

 1 to 1.5 cm. apart ; radial spines 6 to 8, 8 to 10 mm. long, white ; central spine 

 solitary, 10 to 50 mm. long, brownish to black ; flowers purple, 5 to 8 cm. long ; 

 perianth segments narrow, oblanceolate, acute. "Alicoche" (Tamaulipas)! 



20. Echinocereus pentalophus (DC.) Riimpler; Forst. Handb, Cact. ed. 2. 

 774. 1885. 



Cerexis pentalophus DC. M§m. Mus. Hist. Nat. 17: 117. 1828. 



Cereus propinquus DC; Salm-Dyck, Allg. Gartenz. 1: 366. 1833. 



Echinocereus leptacanthus Schum. Gesamtb. Kakt. 260. 1898. 



Eastern Mexico. Southern Texas. 



Procumbent, with ascending branches, deep green ; ribs 4 to 6, somewhat 

 undulate, bearing low tubercles; radial spines 4 or 5, very short, white 

 with brown tips; central spine 1, rarely wanting; flowers reddish violet, 7 

 to 12 cm. long ; perianth segments broad, rounded at apex ; scales on the ovary 

 and flower tube bearing long cobwebby hairs and brownish spines. 



21. Echinocereus sciurus (K. Brandeg.) Britt. & Rose, Cactaceae 3: 22. 1922. 

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



Southern Baja California ; type from San Jos6 del Cabo. 



Densely cespitose, with many individuals forming clumps sometimes 60 cm. 

 broad; stems slender, often 20 cm. long, often nearly hidden by the many 

 spines; ribs 12 to 17, low, divided into numerous tubercles 5 to 6 mm. apart; 

 areoles small, approximate, circular, at first woolly, becoming naked ; radial 

 spines 15 to 18, sometimes 15 mm. long, slender, pale except the brownish tips ; 

 centrals usually several, shorter than the radials ; flowers described as 7 cm. 

 long, about 9 cm. broad when fully open ; inner perianth segments in 2 to 4 

 rows, bright magenta ; seeds 1 mm. long, tuberculate. 



