trees resulting from these nuts with the native American, for 
height growth. 
(2) The American pollen used was kindly furnished us by 
the U. S. Dept. of Interior, and was 
Prof. H. M. Jennison o 
collected from a tree (unfortunately badly eg at an eleva- 
tion of about 4000 feet near Mt. Sterling ¢ zap, N. C. A second 
lot of pollen sent us by Prof. Jennison, from a eee Ameri- 
can on Thunderhead Mountain, N. C., at 5000 ft. elevation, yielded 
f various species and hybrids. A 
no result after pollination « 
pollination of “S&” with a good American parent is very desir- 
Ve in order to give offspring with a greater height growth. We 
have 14 of these hybrids and 14 of the reciprocals. See 
2 
alread 
table, 
oy ot “ combination of Smith Hybrid with the Japanese chest- 
- 
Pp. 
ie 
nut, 1.e., a“ back cross,” is a good one because the pollen used here 
was from the fine Japanese tree of Mr. Paul Hammond at Syosset, 
Long Island. This tree is one of the parents of the splendid 
hybrid figured in last year’s report. 
(4) This is one of the most important items in the table because 
these are the second generation of Japanese-American hybrids. 
Growth Rates of Hybrids at the Hamden Plantation —The fol- 
lowing table gives various data on the growth rates of the different 
hybrids, 188 in all, now growing at Hamden, Conn, The data 
were taken at the end of the growing season, on October 12, 1936. 
If we compare the figures with those of our report for 1935, 
it will be seen that on the whole there was a somewhat greater 
erowth in 1936. As the trees become older their rate of growth 
in length increases somewhat. How long this will continue we 
do not know. Careful records are being kept of the growth of 
each individual from year to year. We find that the phenomenon 
of hybrid vigor as expressed in rapid growth is constant from 
year to year; i.e., if a given hybrid grows 3 feet in one year, it 
will approximate the same length growth next vear, ete. The 
remarkable Japanese-American hybrid figured in last year’s report, 
then 11 feet 2 inches tall, was this year 14 feet 101% inches, making 
a growth of nearly 4+ feet. In 1935 it grew 4+ feet 2 inches. The 
not show the heights of these largest individuals; they 
tables de 
are of course buried in the averages. We report a few of the 
outstanding ones in the table on page 54. 
