ECHINOCEREUS. 



31 



Collected near Guaymas, Mexico, March 10, 1910, by Rose, Standley, and Russell 

 (No. 12570, type), andbylvanM. Johnston, April 14, 1921 (No. 3103). It also was found 

 as far south as Topolabampo, Sinaloa, March 23, 19 10, by Rose, Standley, and Russell 

 (No. 13349) an(i at San Pedro Bay, Sonora (No. 4291), and at San Carlos Bay, Sonora 

 (No. 4344) , by Mr. Johnston in 192 1 . 



It is related to E. rcichenbachii, 

 but is very distinct from it. 



Mr. Johnston's No. 3103 flow- 

 ered in Washington, July 22, 1921. 



Figure 34 is from a photograph 

 made in Washington from a living 

 plant collected by Rose, Standley, 

 and Russell at Topolabampo, 

 Mexico. 



40. Echinocereus roetteri (Engelmann) 

 Riimpler in Forster, Handb. Cact. 

 ed. 2. 829. 1885. 



Cereus dasyacanthus minor Engel- 

 mann, Proc. Amcr. Acad. 3: 279. 

 1856 

 Cereus roetteri Engelmann, Proc. 



Amer. Acad. 3: 345. 1856. 

 Echinocereus kunzei Gtirke, Mcnats- 

 schr. Kakteenk. 17: 103. 1907. 



Cespitose, or perhaps sometimes 

 simple and occasionally budding above, 

 1 to 2.5 dm high; ribs 13, straight, 

 more or less undulate ; areoles circular, 

 or a little longer than broad, about 1 

 cm. apart; radial spines 15 to 17, aci- 

 cular, about 1 cm. long, white or pur- 

 plish; central spines 1 to 5, not in a 

 single row, a little stouter but scarcely 

 longer than the radials; flowers appear- 

 ing below the top of the plant, large, 6 to 



7 cm. long, perhaps even broader than long, light purple; outer 

 perianth-segments greenish yellow; inner perianth-segments 

 oblanceolate, acute, 3 to 4 cm. long; ovary and fruit spiny. 



Type locality: Near El Paso, Texas. 



Distribution: Southwestern Texas; Chihuahua, near 

 El Paso, and southeastern New Mexico. 



Echinocereus kunzei which we have referred here as 

 a synonym is usually stated to be from Arizona. It 

 was doubtless sent out from Phoenix, Arizona, where 

 Dr. Kunze lived, but we have a specimen in the U. S. 

 National Herbarium labeled "southern New Mexico" 

 in Dr. Kunze's handwriting. The illustration which 



Fig. 34. Echinocereus scopulorum. 



Figs. 35 and 36. Flower and spine-clusters 

 of Echinocereus roetteri. X0.9. 



Dr. Kunze uses (Price List of Cactaceae, 191 3) suggests 

 Echinocereus viridiflorus. 



According to Engelmann it is similar to E. dasyacanthus from which it is distinguished 

 by its fewer ribs, stouter spines, purple flowers, smaller fruit, and larger seed. 



This species was named for Paulus Roetter, the artist, who made the cactus drawings 

 for the Mexican Boundary Survey. 



Illustrations: Cact. Mex. Bound, pi. 41, f. 3 to 5, as Cereus roetteri; Bliihende Kakteen 

 3: pi. 128, as Echinocereus kunzei. 



