8 BULLETIN 1195, U. S. DEPARTMENT OF AGRICULTURE. 
THE ABILITY' OF CULTIVATED VARIETIES TO PRODUCE SEED. 
The innate ability of varieties to produce seed can be judged best 
when the pollinations involve pollen that is most highly potent and 
viable and are made when flowers open in abundance. Results from 
proper pollinations with pollen varieties placed in class 1, especially 
of McCormick, Keeper, Busola, Clio, Mclntyre, and Seedling 24642, 
are much more reliable than when pollen of varieties in class 2 are 
used, and from the results of such crosses the following classes may be 
made with reference only to ability to produce fruit: 
Class A. — Varieties highly productive of seed balls when pollen of varieties in 
class 1 is used. 
Class B. — Feeble production of seed balls to the viable pollen of varieties in class 1. 
Class C.— No production of seed balls with seed to any pollination. 
Class D. — A fourth grouping, designated as class D. may be made on the basis of the 
tendency to produce parthenocarpic and seedless fruits evidently without fertilization. 
A survey of the results of pollinations reported by Stuart {2J+) and 
those here recorded in Table 1 shows that when blooming well, many 
varieties readily produce seed balls provided pollen known to be 
viable is used. 
Table 1. — Potato crosses grouped according to pollen parent recorded by the United 
States Department of Agriculture during the 9-year periodfrom 1914 to 1922, inclusive. 
[The crosses recorded for the years 1914 to 1918, inclusive, were made by William Stuart, P. M. Lombard, 
and others.] 
Date of 
crossing. 
Parents. 
May 26, 1921 Burbank x American Giant 
Aug. 11,1915 j White McCormick X American Wonder. 
Aug. 7, 1914 | Burbank x Beauty of Hebron 
Aug. 8, 1914 I Green Mountain x Beauty of Hebron. . . 
Total and average 
Aug. 10, 1914 j British Queen X Bohun 
Aug. 8,1914 j Rust Proof x Bohun 
Do. ; State of Maine X Bohun 
Total and average. 
Aug. i } 
Do. 
Aug. 10, 
Aug. 13, 
Aug. 10, 
Aug. S, 
Aug. 7, 
Do. 
Do. 
July 28, 
Aug. 7, 
Aug. 8, 
Aug. 7, 
Do. 
July 28, 
Aug. 8, 
Do. 
Aug. 9, 
July 27, 
Aug. 7, 
Aug. 15, 
July 29, 
Aug. 8, 
Aug. 10, 
Aug. 10, 
1914 i 
1914 ! 
1915 
1914 • 
1914 
1914 
1916 
1914 
1914 
1914 
1914 j 
1915 
1916 I 
1914 I 
1915 j 
1916 
1914 I 
1914 
1915 
Acme X Busola 
Beauty of Hebron x Busola 
British Queen X Busola 
Cacha Negra (S. A. No. 7) X Busola. 
Carman No. 3 X Busola 
Charles Downing X Busola 
Country Gentleman X Busola 
Early Michigan X Busola 
Early Rose X Busola 
do 
Early Thoroughbred X Busola 
Farmer x Busola 
Flourball X Busola 
Garnet Chili X Busola 
do 
Gold Coin X Busola 
Green Mountain X Busola 
do 
.do. 
Irish CobblerX Busola. 
do 
do 
Late BlightlessX Busola. 
Late Vicktor X Busola — 
ManilaXBusola 
involved 
■X3 
AX- 
-X3 
AX3 
BX1 
-XI 
—XI 
Number of— 
Flowers £*£ ! 
crossed - prXced, 
Percent- 
age of 
success. 
AX1 
AX1 
BX1 
AX1 
AX1 
BX1 
A XI j 
AX1 I 
AX1 : 
AX1 
-XI 
-XI | 
AX1 
axi ! 
AX1 ! 
AXI i 
AXI 
AXI 
AXI 
AXI 
AXI 
AXI 
AXI 
AXI | 
AXI 
1 
18 i 
2 
1 
50.00 
9 
7 
77.78 
12 
C 

39 
17 
43.59 
17 
8 
47.06 
6 


8 
5 
62.50 
fi 
7 
87.50 
10 
6 
60.00 
9 
8 
88.89 
. 4 


15 
2 
13.33 
•; 
3 
50.00 
16 
6 
37.50 
s 
4 
50.00 
o 
1 
20.00 
2 


40 
17 
42.50 
68 
20 
29.41 
17 
10 
58.82 
296 
119 
40.20 
128 
82 
64.06 
17 
7 
41.18 
6 
5 
83.33 
48 
31 
64.58 
