Morphological Variations at Different Stages of Growth in Normal, Cytoplasmic Male‐Sterile, and Restored Versions of Zea mays L. 1

MALE sterility is associated with the formation of little or no pollen and shriveled anthers. Other morphological differences between normal and male-sterile maize plants are reduction of stalk length above the ear, individual internodes, and tassel culms in male-sterile plants (4). Shortening of internodes in the mature plant is not always sequential and certain internodes of the sterile version may be longer than those of the corresponding normal version. The restored version is erratic in its expression. Usually, the tassel culms are not shortened but the number of internodes above the ear is reduced. Jones (6) also noted a reduction in the tassel culm in male-sterile corn but not in restored versions. He believed that pollen reduction had something to do with the shortening of the internodes. Some morphological differences associated with male sterility in other plants were described in a previous paper (4). Male sterility also has been found to reduce plant height significantly in male-sterile sweet corn plants and in sterile X restored hybrids (5). Since height to the top ear in these plants was not affected, shortening resulted from reduction of the stalk above the ear. Nonsignificant differences were obtained for length of time to 50% silking within lines. However, the interaction among the crosses was significant. Allard (1) observed complete correlation between male sterility in lima beans and a seedling abnormality which caused shorter plants, but the sterile plants eventually exceeded the normals because of longer vegetative growth. These two characters were thought to result from pleiotropism or 'linkage but more likely the former. An association in Oenothera crosses (8) existed between pollen breakdown, and leaf width and color. Corolla characters and sterility were related in an interspecific Njcoticma cross, but could not be distinguished be-