12 BULLETIN 624, U. S. DEPARTMENT OF AGBICTJLTURE. 
NAVEL STRAIN. 
The trees of the Navel strain have habits of growth and produc- 
tion similar to those of the Valencia strain. The foliage is usually 
rather dense; the leaves are small and rather pointed in shape. 
The typical fruits, as shown in Plate XI, resemble the fruits of the 
Valencia strain in shape, size, and color, but differ from them in 
having a smoother texture of skin, thinner rind, more acid juice, 
fewer seeds, and a small, often rudimentary navel. This strain occurs 
occasionally as individual fruit and limb sports in trees of the Valencia 
strain. It has been isolated in commercial propagation and is grown 
to a limited extent under the name Navelencia orange. This strain 
is especially interesting from the fact that there is a possibility of 
isolating from it by bud selection a seedless strain of the Valencia 
variety. 
WILLOW-LEAF STRAIN. 
The trees of the Willow-Leaf strain have spreading and drooping 
habits of growth, very narrow, willowlike leaves, and produce infre- 
quent, light crops of fruit. 
The typical fruits, as shown in Plate XII, are somewhat flattened; 
size usually small; color yellowish; texture of skin very coarse; rind 
thick, ridged, and uneven; rag coarse; juice scant, of poor quality; 
seeds averaging about 2 per fruit. This strain, while one of the most 
interesting bud variations found in this variety, is absolutely worth- 
less for commercial purposes. 
INDIVIDUAL VARIATIONS OF FRUITS. 
The individual fruit variations found in trees of many of the 
Valencia orange strains are of fundamental importance in considering 
the origin of the various strains and their widespread distribution in 
young orchards. Under normal conditions a twig originating as a 
bud variation and bearing only a single variable fruit will in a few 
years develop into a large branch bearing the same character of fruit. 
In securing bud wood for propagation according to the methods which 
have prevailed in the past, no thought has been given to the possible 
occurrence in the trees of branches bearing fruits of variable strains, 
and as a result among trees so propagated there is usually found a 
considerable proportion of variable ones. On account of this previous 
lack of knowledge of the existence of variable strains, the percentage 
of such variable-strain trees in the population of any locality has been 
greatly increased with each bud generation. This fact is one of the 
most important reasons for securing individual-tree performance rec- 
ords and using such records as guides in the selection of trees from 
which to obtain bud wood for propagation. 
