STANDLEY TEEES AND SHRUBS OF MEXICO. 923 



indric, 5 to 16 cm. long ; ribs 8 to 10 ; areoles 10 to 12 mm. apart ; radial spines 

 about 10, spreading; central spines 4, stout and angled, 2.5 to 3.5 cm. long; 

 flowers 3 to 4 cm. long, arising from near the top of the plant, light yellow ; in- 

 ner perianth segments oblanceolate, rounded at apex; ovary not very spiny. 



13. Echinocereus subinermis Salm-Dyck in Seem. Bot. Voy. Herald 291. 

 1856. 



Cereus subinermis Hemsl. Biol. Centr. Amer. Bot. 1: 546. 1880. 



Northern Mexico ; type collected near Chihuahua. 



At tirst simple, 10 to 12 cm. high, afterwards a little branching at base, 

 when young pale green, afterwards bluish and finally darker green, erect; ribs 

 5 to 8, broad, somewhat sinuate ; spines all radial, small, conic, 1 to 2 mm. 

 long, yellow, 3 or 4, deciduous ; flowers 5 to 7 cm. long, yellow ; perianth seg- 

 ments oblanceolate, acute ; spines of areoles on ovary and flower tube short, 

 white. 



14. Echinocereus luteus Britt. & Rose, Contr. U. S. Nat. Herb. 16: 239. 1913. 

 Sonora and Sinaloa ; type from Alamos, Sonora. 



Stem short to elongate, sometimes branching near base, bluish green, more 

 or less purplish, 8 or 9-ribbed ; ribs rather thin, barely undulate, rounded ; are- 

 oles small, 10 to 12 mm. apart ; spines small, the radials 6 to 8, unequal, 2 to 

 8 mm. long, widely spreading, white with darker tips ; central spine single, 

 porrect ; areoles on ovary and flower tube bearing white wool and light-colored 

 spines with dark tips ; flowers pale yellow, sweet-scented, 7 cm. long ; outer 

 perianth segments streaked with red ; inner perianth segments lemon-yellow, 

 oblanceolate, acute. 



15. Echinocereus chloranthus (Engelm.) Riimpler ; Forst. Handb. Cact. ed. 

 2. 814. 1885. 



Cereus chloranthus Engelm. Proc. Amer. Acad. 3: 278. 1856. 



Northern Mexico. Western Texas and southern New Mexico ; type from El 

 Paso. 



Cylindric, usually simple, 8 to 15 cm. long, 5 to 7 cm. in diameter ; ribs 

 about 13, often nearly hidden by the densely set spines; areoles nearly cir- 

 cular ; radial spines several, spreading ; centrals 3 or 4, not angled, in a ver- 

 tical row, one much more elongate than the others, 2 to 3 cm. long; flowers 

 yellowish green, 2 cm. long ; fruit nearly globular, 5 to 10 cm. long, dark 

 purplish red, covered with small bristly spines ; seeds black, dull, pitted, the 

 hilum nearly basal, round. 



16. Echinocereus g-randis Britt. & Rose, Cactaceae 3: 18. 1922. 



Islands of Baja California ; type from San Esteban Island. 



Stems usually single or in small clusters, subcylindric, 10 to 40 cm. high, 

 8 to 12 cm. in diameter; ribs 21 to 25, low; areoles large, longer than broad, 

 about 1 cm. apart ; spines dull white or cream-colored, rather short and stiff, 

 the radials 15 to 25, the centrals 8 to 12, often in 2 rows; flower 5 to 6 cm. 

 long, unusually narrow, with a short limb ; ovary and flower tube densely 

 clothed with clusters of pale straw-colored spines intermixed with white 

 hairs; outer perianth segments white, with a green medial line, inner ones 

 narrow, 1.5. cm. long, white with green bases; fruit densely spiny. 



17. Echinocereus dasyacanthus Engelm. in Wisliz. Mem. North. Mex. 100. 

 1848. 

 Cereus dasyacanthus Engelm. in A. Gray, PI. Fendl. 50. 1849. 

 Echinocereus spinosissimus Walton, Cact. Journ. 2: 162. 1899. 

 Echinocereus rubescens Dams, Monatsschr. Kakteenk. 15: 92. 1905. 

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



