The wild cotton plant (Thurberia thespesioides) in Arizona 
VERNON BAILEY 
(WITH TWO TEXT FIGURES) 
The wild cotton plant, which harbors a native cotton boll 
weevil Anthonomus grandis Thurberiae,* is common in certain 
localities in the mountains of southern Arizona. To determine the 
vertical, or zonal, range of the plant and weevil I visited, from 
October 19 to November 15, many of the mountain ranges where 
the plant was known to occur and others where it might occur, 
and gathered such data on its distribution, abundance and habits 
as the limited time would admit. Additional information was 
obtained from Professor J. J. Thornber, of the State University 
at Tucson. 
DISTRIBUTION 
The plant was studied mainly in the Santa Catalina and 
Santa Rita Mountains, and in the mountains about Globe and 
Roosevelt. The Dragoon, Graham, Pinal, Tortilla, Salt River, 
and Date Creek Mountains were visited without finding it. 
In Sabino Canyon, on the south side of the Santa Catalina 
Mountains, where both Thurberia and the weevil are abundant, 
the limits of range on various slopes were worked out with great 
care. These limits are given in some detail as the subsequent 
localities showed little or no extension of zonal range. The lowest 
Thurberia plants found were at 3,600 feet on a west slope, 600 
feet above the bottom of the canyon, and they were common at 
3,800 feet on other west slopes. On open southwest slopes in the 
upper part of Sabino Canyon they began at 4,000 feet and ex- 
tended up to 5,000 feet in the upper division of Lower Sonoran 
zone. That is they range from the upper limits of giant cactus 
and paloverde to the lower limits of juniper, nut pine, and Emory 
oak. This range seems to hold true except that Thurberia occurs, 
so far as I can learn, only on south, west or east slopes and conse- 
quently does not go so low as do most of the plants of its zonal 
* Pierce, Jour. Agr. Research 1: 90. 10 N 1013. 
301 
