During 1950 work was completed on the inheritance, morphology, functioning of pollen and gynoecia, and other tests conducted in an attempt to the ascertain the causes of unfruitfulness of these mutants. Under field conditions each is highly unfruitful. All have the normal diploid chromosome number, and with the exception of Cl\1\ each behaves as if determined by a single recessive gene.
ap (apetalous) 43Ll6-9 var. Early Santa Clara. Corolla segments are variably, but usually greatly reduced. Since anthers are also reduced, pollen is scarce and nonfunctional, this mutant is generatively male-sterile.
Cl\1\ (cleistogamous) 44L50-84 Var. San Marzano. Incomplete dominant. Corolla segments of Cl\1\Cl\1\ do not separate from each other either in late bud stage or at anthesis and are significantly smaller than normal. The complete unfruitfulness of this homozygote can be explained by (1) lack of hormonal stimulation adequate to prevent premature abscission of flowers and (2) failure of anthers to shed pollen. Corolla segments of the hererozygote usually separate slightly and the plants usually bear a few fruits. Expression of the floral character is more intense in the winter greenhouse than in the field.Although the possability that anthers fail to shed pollen has not been entirely ruled out, the cause of unfriitfulness of the heterozygote has not been clearly demonstrated.
cl\2\ (cleistogamous) 47L2-185 Var. San Marzano. In respect to its partial opening of flowers cl\2\cl\2\ resembles cl\1\+, but differs in being completely recessive, having leaves of modified shape, darker green color and shorter internodes. Flowers appear nearly normal in the greenhouse but vegetative characters remain distinct. This mutant is potentially fertile, but since anthers usually fail to shed pollen it is mechanically male-sterile. It offers some promise as a male sterile for mass hybridization.
ex (exserted) 47L2-191 Var. San Marzano. The only apparent deviations of this mutant are the greatly elongated and consequently exserted stigma and high ovule sterility. In about 30% of the flowers stigmas do not emerge and styles are twisted and curled within the anther tube. The projection of the stigma tends to prevent self-pollination if the exserted flowers and can account for the observed unfruitfulness. This mutant seems to differ from the one described by Currence (Proc. Amer. Soc. Hort. Sci. 44:403-406. 1944) in the variable expression and determination by a single gene of the former.
pi (pistillate) 44L50-137 Var. San Marzano. The flower is modified in many ways. Stamens, except for occasional rudiments are absent. Corolla and calyx are attenuate. Pistil is usually distated and often adnate to adjacent organs. Inflorescences resemble lf in always continuing growth as a vegetative shoot.
vg (vegetative) 44L2-171 Var. San Marzano. All parts of the flower are reduced in size and number and are usually so greatly modified that they are scarcely recognized as flowers. Although potentially fertile, this mutant is highly unfruitfulbecause the flowers are too greatly deformed to permit normal self-pollination. (a complete account has been submitted to the American Journal of Botany)