20 
The Journal of Heredity 
TABLE I.—Height of Catalpa Bignonioides, of C. Kaempferi, of Their Hybrid, and of C. spectosa 
(average, in feet, of ten trees grown, at Mt. Carmel). 
C. bignonioides* 
Year | Age | C. bignonioides | C hamaieri C. kaempferi C. speciosa 
1912 1 02 0.4 0.2 1913 | 0.8 
1913 2 1.5 eS 0.8 1914 |e 
1914 3 BT 4.9 2.6 1915 6.9 
1915* 4 9.9 8.7 ay 1916 9.2 
1916 i 7.4 OFS 5.8 19007) | Sees 
1917 6 HOS iWies 8.2 1918; |) Sige 
1918 7 11.4 13.1 9.1 Slets “ 
* Trees severely damaged by wind breakage so that all plants were cut to the ground and only one sprout allowed 
to grow the following year. 
decided to cut the trees to the ground 
before the following growing season. 
It is the usual practice with catalpas, 
when they are grown for timber,to cut 
them back after one or two years as the 
trunks are then straighter and the trees 
make fully as much growth in the end 
as when they are not cut back. After- 
wards the trees were limited to one 
sprout. 
The greater growth of the hybrid was 
easily apparent after the trees were well 
started, as shown by the figures in the 
table and the trees shown in Fig. 7. 
The increased vigor of the hybrid is even 
more than that indicated by the figures. 
The larger parent at Mt. Carmel, C. 
bignonioides, did not flower until 1918, 
and then produced only a few pods on 
one or two trees. The Japanese species 
flowered in 1915 and every following 
year. The cross likewise flowered with 
it. In addition, therefore, to making a 
larger vegetative growth, the cross has 
expended energy each year upon seed 
formation, which the larger parent has 
not done to any appreciable extent. In 
the profusion of its bloom and the 
abundance of seed this cross is a re- 
markably fine illustration of the vigor 
frequently derived from species hybrids. 
In amount of seed produced, it is from 
five to ten times more productive than 
either parent, a notable instance of the 
temporary advantage given to some 
crosses in natural competition. 
As grown at Mt. Carmel, in the south- 
ern part of the state, both parents and 
their offspring have proven to be per- 
fectly winter-hardy. At Portland, about 
30 miles north, the bignonioides parent 
has suffered severely. During the latter 
years it has been killed to the ground 
every winter, growing from the base 
each spring in a mass of sprouts. The 
Japanese parent and the cross have so 
far been unharmed. Although the dis- 
tance is small between these two 
localities, it should be remembered that 
one passes from one biological zone to 
another (Upper Austral to Transitional) 
in going from Mt. Carmel to Portland, 
Conn. The advantage which the hy- 
brid has over both parents is conse- 
quently much accentuated as C. Kaemp- 
fert is naturally a small grower. The 
combination of the two species, possess- 
ing the larger growth of one parent 
together with the greater viability of the 
other, far surpassed either parent in 
this location. 
INHERITANCE OF PARENTAL 
CHARACTERISTICS 
The detailed characteristics of each 
parent, and the way they are expressed 
in the hybrid, are arranged in Table II. 
There is an intimate mingling of the 
features of both parents, so that this 
plant affords a good example of a species 
cross of the type studied with so much 
interest by the early hybridists such as 
K6lreuter, Gartner, Focke and others. 
It is not strange that investigators, 
working with such material as this, did 
not make much progress in arriving 
at any definite principles of here dity 
While some characters in this illustra- 
