STANDLEY TREES AND SHRUBS OF MEXICO. 925 



23. EcMnocereus cinerascens ( DC. ) Riimpler; Forst. Handb. Cact. ed. 2. 786. 

 1885. 



Cereus cinerascens DC. Mem. Mus. Hist. Nat. 17: 116. 1828. 



Cereus deppei Salm-Dyck, Hort. Dyck. 338. 1834. 



EcMnocereus cirrhiferus Riimpler ; Forst. Handb. Cact. ed. 2. 778. 1885. 



EcMnocereus glycimorplnis Riimpler; Forst. Handb. Cact. ed. 2. 800. 1885. 



Central Mexico. 



Growing in patches 60 to 120 cm. broad, branching at base, the stems as- 

 cending to about 30 cm. ; ribs about 12, not very prominent, obtuse ; areoles 

 rather scattered, orbicular ; spines white or pale, straight, rough, 1.5 to 2 cm. 

 long ; radials about 10 ; centrals 3 or 4 ; flowers 6 to 8 cm. long, the tube very 

 short ; scales on ovary and tube small, acute, their axils crowded with short 

 white wool and 6 to 8 long white bristles ; inner perianth segments, when dry, 

 deep purple, 3 to 4 cm. long, obtuse. 



23. Echinocereus adustus Engelm. In Wisliz. Mem. North. Mex. 104. 1848. 

 EcMnocereus rufispinus Engelm. in Wisliz. Mem. North. Mex. 104. 1848. 

 EcMnoceretis radians Engelm. in Wisliz. Mem. North. Mex. 105. 1848. 

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

 Chihuahua ; type from Cosihuiriachi. 



Simple, short-cylindric, often only 4 to 6 cm. higli ; ribs 13 to 15 ; areoles 

 closely set, elliptic; radial spines 16 to 20, appressed-pectinate, pale, the 

 central spines wanting or solitary, sometimes elongate and porrect ; flowers 

 purplish, 3 to 4 cm. long ; inner perianth segments narrow ; ovary and calyx 

 tube covered with clusters of short brown spines and long wool. 



24. EcMnocereus reichenbachii (Terscheck) Haage; Ind. Kew. 2: 813. 1893. 

 EcMnocactus reichenhacMi Terscheck; Walp. Repert. Bot. 2: 320. 1843. 

 Cereus caespitosus Engelm. Bost. Journ. Nat. Hist. 5: 247. 1845. 

 EcMnocereus caespitosus Engelm. in Wisliz. Mem. North. Mex. 110. 1848. 

 Cereus reichenbacManus Labouret, Monogr. Cact. 318. 1853. 

 EcMnocereus rotatus Linke, Wochenschr. Giirtn. Pflanz. 1: 85. 1858. 

 Northern Mexico. Texas. 



More or less cespitose ; stems simple, globose to short-cylindric, 2.5 to 20 cm. 

 long, 5 to 9 cm. in diameter ; ribs 12 to 19 ; areoles approximate, elliptic ; 

 spines 20 to 30, white to brown, pectinate, interlocking, 5 to 8 mm. long, 

 spreading, more or less recurved ; centrals 1 or 2, like the radials, or often 

 wanting; flowers often 6 to 7 cm. long and fully as broad, light purple; 

 perianth segments narrow, the margin more or less erose; fruit ovoid, about 

 1 cm. long; seeds black. 



25. Echinocereus rigidissimus (Engelm.) Rose, Contr. U. S. Nat. Herb. 12: 

 293. 1909. 



Cereus pectinatus rigidissimus Engelm. Proc. Amer. Acad. 3: 279. 1856. 



Sonora. Southern Arizona. 



Plants simple, erect, rigid, short-cylindric, 10 to 20 cm. high, 4 to 10 cm. in 

 diameter, usually hidden by the closely set interlocking spines; ribs 18 to 

 22, low; areoles approximate, elliptic, 5 to 6 mm. long; radial spines about 

 16, gray to reddish brown, arranged in horizontal bands, pectinate, rigid, 15 

 mm. long or less, often recurved ; central spines none ; flowers purple, 6 to 7 

 cm. long, fully as broad when expanded ; perianth segments oblong, 3 to 4 cm. 

 long, acute; areoles on ovary somewhat floccose, very spiny; fruit globular, 3 

 cm. in diameter, very spiny; seeds black, tuberculate, 1.5 mm. in diameter. 

 " Cabeza del viejo." 



This species is often cultivated under the name of rainbow cactus. 



