BUD VARIATION IN" THE WASHINGTON" NAVEL ORANGE. 17 



of the Washington strain every season during the period of observa- 

 tion. From the standpoint of the study of the behavior of citrus- 

 fruit variations, this strain is one of the most interesting of those 

 under consideration. 



The trees of the Thomson strain are heavy and regular bearers, 

 have an open and drooping habit of growth, dense foliage, and large 

 dark-green leaves. As a rule, the trees of this strain are not as 

 vigorous growers as those of the Washington strain under similar 

 conditions. 



The fruits, illustrations of which are shown in Plate III, are similar 

 in shape and size to those of the Washington strain. They differ 

 from them mainly in having a very smooth rind of a bright reddish 

 orange color. The rind of the Thomson fruits is thinner and the rag 

 is more abundant and coarser than that of the fruits of the Wash- 

 ington strain. The smooth texture, bright reddish color, and hand- 

 some appearance of the fruits is of distinct value from the market 

 standpoint. The juice usually is less acid than that of oranges of 

 the Washington strain and is lacking somewhat in flavor. The 

 undesirable characteristics of the rag and the inferior quality of the 

 juice are detrimental to the reputation of the fruits of this strain. 

 The fruits are seedless and the navels variable in size and arrange- 

 ment, usually medium to small, occasionally rudimentary. 



Among the interesting fruit variations observed in the Thomson 

 trees are those having the Thomson rind characteristics and the 

 Washington rag and juice quahties, a Thomson-Washington strain; 

 and the reverse of this condition, a Washington-Thomson strain. 



AUSTRALIAN STRAIN. 



The name Australian seems to have been used frequently on 

 account of the resemblance of the trees of this strain to those grown 

 in California from certain Australian importations. It has gradually 

 been adopted by citrus growers to indicate the rank-growing, unpro- 

 ductive Washington Navel trees which bear coarse, inferior fruits. 

 As a matter of fact, the name is used frequently to include several 

 distinctly inferior variations of the variety and it is here used in 

 this collective sense. 1 



The trees, an illustration of which is shown in figure 5, are either 

 regularly unproductive or produce crops at irregular intervals. The 

 typical trees have a peculiar upright habit of growth and usually 

 show more than ordinary vegetative vigor. Many trees of this strain 

 produce a very large number of suckers, which until recently have 

 been highly prized for bud wood for use in propagation. The foliage 

 normally is sparse and the leaves are comparatively small, narrow, 



1 In Bulletin 1, Division of Pomology, U. S. Department of Agriculture, on p. 67, under the head of 

 "Navel (Australian)," the following statement concerning the origin of this strain occurs: "Originally 

 from Bahia, Brazil, by way of Australia and California. Tree shy bearer." 



14575°— 18— Bull. 623 2 



