echinocereus. 
31 
Collected near Guaymas, Mexico, March 10, 1910, by Rose, Standley, and Russell 
(No. 12570, type), and by Ivan M. Johnston, April 14, 1921 (No. 3103). It also was found 
as far south as Topolabampo, Sinaloa, March 23, 1910, by Rose, Standley, and Russell 
(No. 13349) and at San Pedro Bay, Sonora (No. 4291), and at San Carlos Bay, Sonora 
(No. 4344), by Mr. Johnston in 1921. 
It is related to E. reichenbachii, 
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 dasyacantlius minor Engel¬ 
mann, Proc. Amcr. Acad. 3: 279. 
1856 
Cereus roetteri Engelmann, Proc. 
Amer. Acad. 3: 345. 1856. 
Echinocereus kunzei Giirke, 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- „ 
t 1 .1 , r, ■, 1 1 ^ j pig . 34. — Echinocereus scopulorum. 
mg 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 
Dr. Kunze uses (Price List of Cactaceae, 1913) 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 
Figs. 35 and 36.—Flower and spine-clusters 
of Echinocereus roetteri. X0.9. 
3: pi. 128, as Echinocereus kunzei. 
