8 BULLETIN 815, U. S. DEPARTMENT OF AGRICULTURE. 
The importance of the Open strain lies in its tendency to fruit- 
fulness during all seasons of the year under normal conditions. In 
this respect it is more desirable than the Lisbon strain. The trees 
have not been as productive as those of the Lisbon strain and have not 
shown as great resistance to unfavorable climatic conditions, such 
as low temperature or extreme heat, as the trees of the Lisbon strain. 
Fig. 2.—A typical lemon tree (25 years old) of the Open strain of the Lisbon variety, No. 1-34-11 in the 
ee -record plat, showing the open habit of growth characteristic of the trees ofthisstrain. The 
ummarized record of this tree is presented in rank 64 in Table I. 
Therefore, it seems probable that the Open strain is better adapted 
to those sections where the climatic conditions are most moderate, 
as is the case in lemon districts near the coast. The Lisbon strain is 
probably best adapted to interior districts where extremes of heat 
and cold are more likely to oceur. 
DENSE-UNPRODUCTIVE STRAIN. 
The trees of the Dense-Unproductive strain show very vigorous 
vegetative growth. They bear large, pointed leaves and coarse fruits 
having thick rinds and a comparatively small quantity of juice. 
The proportion of trees of this strain in different Lisbon groves 
varies greatly. In some unproductive orchards most of the trees 
belong to this strain. The desirability of eliminating this strain in 
established orchards or in new propagations is emphasized not only 
from the standpoint of low production, but equally, if not more im- 
portant, on account of the production of coarse, inferior fruits, 
which are likely to be very injurious to the reputation of California 
lemons. 
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