310 SEMI-CENTENNIAL OF TORREY BOTANICAL CLUB 
In several cases more than one mistletoe was taken from the 
same host tree. In such cases determinations based on the sap of 
the individual parasites may be compared with a single constant 
for the host plant, or may be compared with the determination 
based on the sample of host leaves nearest the parasite. Differ- 
ences which for some reason indicated by the context are regarded 
as of doubtful value are bracketed. 
Phoradendron californicum Nutt. 
Coll. 531, on Acacia Greggii Gray. Aug. 12. 
A = 2.00, P = 24.0 
For host, A = 1.87, P = 22.5 + 0.13, + 1.5 
On sandy floor of Sabino Creek, near mouth of Sabino Canyon, 
Santa Catalina Mountains. 
Coll. 546, on same species, Aug. 15. А = 1.82, P 231,8 
For host, A = 1.68, P = 20.2 +014, + 1.6 
Small arroyo on bajada between Tucson and Sabino Canyon, 
Santa Catalina Mountains. 
Coll. 535, on Cercidium Torreyanum (S. Wats.) Sarg. Aug. 13. 
A * 1.99, P = 23.9 
For host, A = 1.55, Р — 18.7 + 0144, -. + 52 
Coll. 574, on same species, Aug. 10. A = 2.45, P = 29.4 
No determination for host. 
The first of these collections from Cercidium was taken in the 
same locality as the August 15 sample from A. Greggii. The 
second was taken from a very small shrub in Sabino Canyon, 
on a steep slope about two or three miles below Dam Site. The 
lack of daylight precluded a collection of the very small leaves 
of the host. 
Coll. 267, on Prosopis velutina Wooton, July 6. 
A = 2.65, P = 31.8 
For host, A = 2.64, P = 31.6 +оо, + o2 
Coll. 538, on same species, Aug. 14. A = 2,29, P = 27.5 
For host, A = 2.40, P = 28.8 -011, — 1.3 
These two collections were from the same large mesquite tree, 
on the edge of a small arroyo on the upper bajada, near the mouth 
of Sabino Canyon. The first collection was taken before the 
earlier summer rains, the second after they had fallen. The 
samples of parasites were from different plants. 
