• R. O. Whyte

      Articles written in Journal of Genetics

    • Studies inRanunculus - II. The cytological basis of sex inR. acris L.

      R. O. Whyte

      More Details Abstract Fulltext PDF

      Plants ofRanunculus acris L. were examined to discover the reason for the occurrence in nature of “female,” “minus normal,” “abnormal” and “male” forms.

      The chromosome number of all the plants studied was found to be the same, namelyn = 7.

      In the hermaphrodite “normal” plant it was found that there are two definite phases in the development of the flower; firstly, a male or anther phase, commencing probably with the formation of the anthers, or at least with the delimitation of the sporogenous tissue; secondly, a female or ovule phase, commencing with the development of the ovules, and continuing until embryo sac formation. These two phases are distinctly successive in a hermaphrodite flower; the female phase does not commence until the male phase has been completed by the formation of mature pollen. There is therefore a considerable interval between the male and female reduction processes in any given flower.

      The “female” flower shows these phases as entirely coincident, reduction divisions occurring almost simultaneously; this change in flower development causes the failure of the tapetum in the anthers, with a cessation of pollen formation as a direct consequence.

      An examination of “abnormal” and “minus normal” plants showed that the interval between reduction divisions had been reduced without these processes actually coinciding. There is a direct correlation to be noted between the extent of the reduction interval on the one hand, and the stage of development reached in the anthers on. the other, this latter being governed by the duration of the activity of the tapetum.

      The occurrence of a single “male” plant, in which the reduction divisions coincide as in the “female,” is probably associated with the vascular organisation of the flower. This question is being investigated.

    • Sterility and floral abnormality in the tetraploidSaxifraga potternensis

      R. O. Whyte

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