echinocereus. 
II 
Text-figure 6 is from a photograph of a plant sent to the New York Botanical Garden 
by Dr. Rose in 1913, from near Las Vegas, New Mexico; text-figure 7 shows a flowering 
plant sent to Washington from near Kerrville, Texas, by Mr. B. Mackensen in 1912. 
Fig. 8.—Flower of 
Echinocereus polya¬ 
canthus. X0.6. 
Fig. 9.—Flowering 
branch of Echinocereus 
pacificus. X0.6. 
Fig. 10.—Flower of 
Echinocereus neo- 
mexicanus. Xo.6. 
9 . Echinocereus polyacanthus Engelmann in Wislizenus, Mem. Tour North. Mex. 104. 1848. 
Cereus polyacanthus Engelmann in Gray, PI. Fendl. 50. 1849. 
Cespitose, forming clumps of 20 to 50 stems, pale green but often tinged with red; ribs usually 
10, low; areoles approximate; spines gray when old, at first pale yellow, becoming more or less 
purplish; radial spines about 12; centrals 4, straight, elongated; flowers crimson, 6 cm. long; spines 
on ovary and flower-tube yellow, intermixed with cobwebby wool; fruit and seeds unknown. 
Type locality: Cosihuiriaehi, Chihuahua. 
Distribution: Chihuahua and Durango, 
Mexico, to western New Mexico and south¬ 
eastern Arizona. 
Echinocereus polyacanthus was describ¬ 
ed by Dr. Engelmann in 1848, based upon 
specimens collected by Dr. A. Wislizenus at 
Cosihuiriaehi, a small mining town west of 
the city of Chihuahua. The next year Dr. 
Engelmann transferred it along with the 
other species of his genus, Echinocereus, to 
Cereus, and in 1859, in his report on the 
Cactaceae of the Mexican Boundary, rede¬ 
scribed and illustrated the species; the 
specimens used by him for this report, 
however, were largely from Texas and New 
Mexico, and this additional material repre¬ 
sents a quite distinct species. In order to 
prove this point Dr. Rose in 1908 visited 
Cosihuiriaehi, the type locality, and col¬ 
lected living and herbarium specimens 
which were found to be specifically distinct Fig. 12.—Echinocereus polyacanthus, 
from the so-called E. polyacanthus from the 
El Paso region which now bears the name E. rosei Wooton and Standley. Ihe habit of the 
two species is similar, but the armament is somewhat different and the flowers of the true 
Echinocereus polyacanthus produce an abundance of wool in the axils of the scales which is 
