6 BULLETIN" 697^ U. S. DEPARTMENT OF AGRICULTURE. 



senior writer in 1909 revealed tlie fact that there existed in the grove 

 a striking diversity in the characteristics of the trees. Out of a total 

 of about 500 trees, 123, or nearly 25 per cent, produced fruits having 

 from 30 to 90 seeds in each fruit. The trees bearing these very seedy 

 fruits were found to have a characteristic drooping habit of growth, 

 from which it soon became possible to identify them wherever they 

 occurred in the grove. The fruit from this grove had been guaranteed 

 by the owner to be commercially seedless, and the occurrence of the 

 seedy fruits in the crops, when noticed by the buyers, led to a con- 

 siderable depreciation in their value on the markets. Upon the dis- 

 covery that the seedy fruits were borne only by trees of a certain 

 character, these fruits were eliminated, except those occurring as 

 individual fruit and limb variations, by top-working the trees which 

 produced them, using for this purpose buds selected from trees of the 

 true Marsh strain, which is commercially seedless. One of the trees 

 of the Marsh strain in this grove is shown in Plate II and one of the 

 trees of the Rough S.dedy strain in Plate III. 



An interesting characteristic of the production from individual trees 

 was revealed by the tree-census studies in the Marsh grove first studied. 

 Some of the trees bore very heavy crops, while others, very similar in 

 general appearance to the productive trees, bore only a few fruits. 

 Further observation of this condition during the following years re- 

 vealed the fact that some of the trees possessed the habit of bearing 

 heavy crops one season and light ones the next. The trees having 

 this habit have been called alternate bearers, from the fact that they 

 usually bear full crops only every other year. 



Another strain of trees was found in this grove bearing fruits having 

 a modified pyriform, or bell-like, shape in contrast with the flattened, 

 or oblate, shape of typical fruits of the Marsh strain. These trees 

 have been called the Bell strain on account of the shape of their fruits. 

 This shape, from the market standpoint, is not so desirable as the 

 flattened one of the Marsh strain, and the fruits are likely to be later 

 in ripening than those of other strains. 



The fruits borne by the trees of the Marsh strain have a compara- 

 tively thin rind of very smooth texture and waxy-white appearance. 

 Some of the trees in the performance-record plat were found to produce 

 fruits having very thick rinds with a rough or coarse texture and yel- 

 lowish color. The fruits of this Rough strain, as a rule, have a shape 

 more nearly round or globular than those of the Marsh strain, while 

 the flesh, juice, and other characteristics are somewhat similar to 

 those of that strain. 



Individual-tree census observations made in other groves located 

 in various citrus districts of southern California have brought out 

 clearly the fact that the trees in these orchards vary in about the same 

 manner as those in the grove described above. More than 25 per cent 



