462 
British Columbia, this and fragilis being the only PLATOPUNTIA forms 
north of our border. The species polyacantha extends from Indian 
Territory and northern New Mexico through Utah to Montana and 
Washington; borealis is the most northern variety, ranging from South 
Dakota and Oregon into British Columbia; platycarpa extends from 
Utah and Colorado to [Idaho and Montana and eastward to Nebraska; 
watsoni extends from New Mexico to Utah, Wyoming, and Nebraska; 
albispina extends from New Mexico to Utah and Indian Territory; 
while the peculiar trichophora is confined to the El Paso region of 
Texas and adjacent New Mexico. It would seem that in this case a 
strong type has spread far northward and has been extensively modi- 
fied. In the case of mesacantha, however, we find our most variable 
type. It is easy to define at least nine varieties of it, but there still 
remain numerous forms unworthy of varietal rank and still not strictly 
typical. Its range is wider even than that of. polyacantha, occupying 
the Arizona region and extending east of the Mississippi, in fact 
closely represented on the Atlantic by opuntia, but, so far as known, 
not extending into British Columbia. The species mesacantha ranges 
from Texas to Minnesota, extending eastward into Indiana and Ken- 
tucky, its variety microsperma accompanying it. The variety macro- 
rhiza has the most northwestern extension, reaching the ‘Big Bend” 
of the Missouri from Texas and Arizona. The form eymochila has a 
range second in extent only to macrorhiza, touching the species in 
Kansas and reaching Utah and Arizona to the west. The remaining 
six varieties are far more restricted: parva in southern Missouri; 
grandiflora on the Brazos in Texas; oplocarpa in western Texas and 
Colorado; greenti in Colorado and Arizona; stenochila in western New 
Mexico; and vaseyi in western Arizona. The only other far northern 
species is fragilis, which begins at the south in southern Colorado and 
adjacent New Mexico and Utah, and extends northward into Montana 
and British Columbia, and eastward to Kansas and Minnesota. The 
species tortispina has an eastern range along the plains, extending 
from northern Texas to Nebraska. The remaining 23 forms are purely 
southwestern, as follows: fusco-atra is a form of eastern Texas; strigil, 
Jilipendula, tenuispina, and arenaria belong to the El Paso region; 
spherocarpa and phecantha major are restricted to New Mexico; pal- 
meri, rubrifolia, and spherocarpa utahensis are forms of Utah; levis is 
peculiar to Arizona; mojavensis and treleasii are restricted to south- 
ern California; chlorotica, basilaris, and rutila belong to the desert 
region of southern California, Arizona, Nevada, and Utah; angustata 
and hystricina extend from southern California to New Mexico, the 
latter also reaching Nevada; procumbens and camanchica extend from 
Arizona to the El Paso region of Texas, the latter also reaching south- 
ern Colorado. The total enumeration of Platopuntias in the south- 
west shows 20 forms in Texas, 17 in New Mexico, 14 in Arizona, 11 in 
southern California, 11 in Utah, and 7 in Colorado. But 4 species are 
reported as yet from Nevada, but this is evidently entirely inadequate. 
