Nov. 10,1913 
Pubescent-Fruited Species of Prunus 
157 
CLIMATIC CONDITIONS 
The principal areas occupied by Prunus iexana are represented by 
fairly complete weather records at Menardville, Fredericksburg, and 
San Antonio 1 and by volunteer records at Burnet, Llano, and Lampasas. 2 
These show that the mean annual rainfall ranges from 22.6 inches in 
the more westerly to 28 inches in the eastern and southern portions. 
The monthly means show a fairly well-distributed rainfall throughout 
the year. December to March constitutes the drier period, with Febru¬ 
ary as the driest month. The study of the monthly records of a number 
of years, however, shows that this section is subject to occasional 
heavy rainfalls almost torrential in character, as well as to periods of 
severe and prolonged drought. A study of the extremes of rainfall at 
San Antonio, a nearly central point in the range of this species, shows 
that during the driest year of the period covered by the record, 1885 
to 1903, only 15,9 inches of rain fell, while the maximum record was 
40.5 inches. The structural characters enabling Prunus iexana , the 
wild peach, to endure these vicissitudes are important features to study. 
The temperature conditions characteristic of this section are those of 
comparatively mild winters, minimum temperatures of 12 0 to 16 0 F. 
being matters of common record, with occasional winters showing 
minimum records of as low as — 2 0 to —4° F. 3 
Minimum temperatures of 50° to 6o° and maximum temperatures of 
6o° to 75 0 F. may be followed in a short time by a norther which will 
lower the temperature to near the zero point, or even below. The extreme 
maximum temperatures experienced in this section are from ioo° to 
105° F. 
NATURAL HYBRIDIZATION 
One of the most striking characteristics of the wild peach is the readi¬ 
ness with which it hybridizes with the native and cultivated plums. This 
is proved by the occurrence of well-marked natural hybrids with the local 
wild plums in at least five widely separated localities within its range. 
The occurrence of natural hybrids between species of plants is unusual 
and in many families rare or unknown. The integrity of our plant forms 
could not be preserved if indiscriminate natural hybridizing were a pos¬ 
sibility. 
Probably among trees and shrubs the most numerous examples of such 
hybrids are afforded by the oaks of the Mississippi Valley and the Western 
States, and a number of these have from time to time received definite 
1 Henry, A. J. Climatology of the United States. U. S. Dept. Agr., Weather Bur., BulletinQ., p. 431-436, 
1906. 
3 U. S. Dept, Agr., Weather, Bur., Climate and Crop Service, Texas Section, v. 1-5, 1897-1901. 
8 There was a record of —4.1* F., at Llano, Feb. 12,1899. U. S. Dept. Agr., Weather Bur., Climate and 
Crop Service, Texas Section, Report, v. 3, no. 5, p. 5, 1899. 
