20 BULLETIN 623, U. S. DEPARTMENT OF AGRICULTURE. 
standpoint of the study of the origin and behavior of Washington 
Navel orange strains arising from bud variations. 
YELLOW WASHINGTON STRAIN. 
The trees of the Yellow Washington strain usually are less produc- 
tive than true Washington Navel trees. The habit of growth is 
somewhat erect and the foliage rather sparse. The leaves are likely 
to be small, slightly pointed, and light green in color. 
The fruits, illustrations of which are shown hi Plate VII, are simi- 
lar in shape, size, and thickness and texture of rind to those of the 
Washington strain, but the color is markedly different, being a light 
yellow, which in some cases becomes orange 3-ellow late in the season. 
The characteristics of the rag and juice are somewhat similar to those 
of the Washington strain, except that as a rule the fruits ripen a little 
earlier and the flesh is markedly lighter in color. The fruits are 
seedless and the navel is usually small to medium in size. In many 
cases the fruits bear characteristic small red stripes, or blotches, 
similar in appearance to those found on many Golden Nugget fruits. 
It is believed by some growers that this strain may prove to be of 
commercial value under certain soil and climatic conditions, and a 
few" small orchards of these trees have been planted. The fruits occur 
as infrequent bud variations in some Washington strain trees in the 
performance-record plats. 
YELLOW THOMSON STRAIN. 
The trees of the Yellow Thomson strain under observation are 
similar in production, habit of growth, and foliage characteristics 
to the Thomson trees. 
The fruits resemble typical Thomson fruits with the exception of 
their color and some characteristics of minor importance. The color 
of the fruits of this strain is yellow to yellowish orange, and they 
frequently show small red markings. As a rule, the fruits seem to 
ripen somewhat earlier than those of the Thomson strain under com- 
parable conditions. This strain holds about the same relation to 
the Thomson that the Yellow Washington holds to the true Wash- 
ington strain. It is of little commercial value and is of interest mainly 
from the standpoint of the study of the variability existing in the 
Washington Navel variety. Individual fruit variations of this strain 
occur frequently in Thomson trees, and occasionally Yellow Thom- 
son limb sports have been found. 
RIBBED STRAIN. 
The habit of growth of the trees of the Kibbed strain resembles 
that of the Washington trees except that usually they are more 
finely branched. As a rule, they are not as productive as Washing- 
