70 



Guayule. 



(8) Near this place 22 seedlings were collected from two areas, each of 



12 square inches; i of 1906, 8 of 1907, and 13 of 1908. 



(9) Station 2, quadrat 4. April 1909. 281 living seedlings, all of which 



germinated during the growing-season of 1908, were collected on 

 100 square meters (plate 17, fig. A). 



(10) Endlich reports finding "as many as 50 young plants around full- 



grown trees" (335, 1905, Eng. tr.). Such a large number is not 

 common, but it is not unusual to find 25 seedlings with two foliage 

 leaves about the base of a single plant. 



From such observations it is clear that in particular areas one may 

 find by chance many more seedlings than could by any fortune develop 

 into mature plants. Other areas, however, are quite bare of them. Again, 

 many seedlings which get started die in the course of time, and there can 

 be no doubt that the percentage of deaths is great. Counting seedlings, 

 therefore, is not a dependable method of determining the rate of repopu- 

 lation. For this purpose it is necessary to make a census of sample quad- 

 rats, making as careful estimates as possible of the sizes and ages of the 

 plants. The data in tables 4 to 13 afford such a census. They are summa- 

 rized in table 25 and are further displayed graphically in fig. 12. 



TABLE 25.- 



llassification of guayule plants from seed according to weight on various 

 quadrats indicated. 



1 It is to be recalled that the larger plants had previously been removed from this quadrat. The 

 estimate marked doubtful is based on the figures of adjoining quadrats, and can only be approximate. 



It is clear that the ratios between small and large plants, as shown 

 in table 25, indicate very different degrees of efficacy in reproduction 

 commencing from the seed. This method is the best available in the 

 absence of actual counts of seedlings year by year, obviously not practi- 

 cable. A few such counts, for future comparison, are given in table 26. 



TABLE 26. 



These few data, the difficulty of obtaining which, ofl account of vari- 

 ous circumstances, was very great, have only suggestive significance. It is 



