260 
AMERICAN JOURNAL OF BOTANY 
[Vol. io. 
developed are practically always irregular nubbins. These clones are 
somatic hermaphrodites; i.e., they appear to be perfect but the pistils are 
sterile. Occasionally other flower types are found in F. virginiana, such as 
completely sterile clones in which pollen formation never proceeds farther 
than the tetrad, but such forms are comparatively rare and need not be 
considered (7). 
Material 
The material to be considered in this paper was the result of crosses 
made at the Minnesota Agricultural Experiment Station in 1915 and 1916. 
The seedlings were later transferred to the Minnesota State Fruit-Breeding 
farm at Zumbra Heights. The individual plants were set in the field where 
they were allowed to multiply for one season. The following season, 
records were made as to the sex condition and the degree of fertility of the 
various clones. In nearly all cases the records obtained are the result of 
observations of the sex condition and fertility of several plants of each 
clone, and therefore probably represent fairly accurately the sex condition 
of these clones under field conditions. A few which did not blossom in 
1917 were left until 1918 when final records were taken. The writer is 
indebted to Mr. John Bushnell for completing the records on certain crosses 
in 1918 while the former was absent in military service. 
Terminology 
For the sake of convenience and clearness in discussing the crosses of 
the various flower types, symbols will be used to represent the various sex 
determiners. Shull (4) suggested in the case of Lychnis the use of the 
symbol FF to represent a female and FM to represent a male, as he deter¬ 
mined that the females were homozygous for the sex determiners whereas 
the males were heterozygous. Similar symbols have been found appropriate 
in interpreting the sex condition in the grape (5). It will be apparent from 
the following discussion that these symbols will not apply in the case of 
the strawberry, since the females are apparently heterozygous for the 
female and male determiners and the males homozygous. Therefore the 
symbols FM and MM will be used to designate the genetic condition of 
the female and male plants respectively of the dioecious wild forms, and 
FH and HH the females and hermaphrodites respectively of the cultivated 
varieties, as it has been shown that the cultivated hermaphrodites have 
probably been derived from partially fertile wild male types (7). In the 
strawberry, as in the grape, it may be assumed that the factor for female¬ 
ness (F) carries linked with it the suppressed male factor, and that the 
functional male factor is linked with a factor for femaleness which is sup¬ 
pressed to the extent that only somatic structures are developed and the 
pistils are sterile. In the case of the hermaphroditic strawberries, the 
female condition is not suppressed, and the pistils are therefore fertile. 
The symbol H then represents the linked factors F and M. 
