Observation of the morphological and anatomical characteristics of different sex flower buds in Trichosanthes kirilowii Maxim.

To clarify flower bud development in Trichosanthes kirilowii Maxim., we investigated the morphological and anatomical differentiation and development of male and female flower buds using stereomicroscopy, paraffin sectioning, and resin slicing. Results showed the Trichosanthes flower to be dioecious, with sexual differentiation observed between the female and male flowers and the development speed of male flowers found to be significantly faster than that of female flowers. The differentiation between male and female flower buds was completed by ~0.2 mm length. The male flower was monosexual and the differentiation stages could be divided into six periods, with only the differentiation and growth of the stamen primordia observed during the whole development process. The female flower was hermaphroditic and the differentiation stages could be divided into seven periods, including joint development of the pistil and stamen, though stamen development regressed at a later stage. Thus, this study clarified the bud development stages, as well as the internal anatomical and external morphological changes and differentiation of male and female flower buds and established a correlation between internal structure differentiation and external morphology of male and female flower buds. Furthermore, this study provides a reference for the identification of early seedlings and research on sexual differentiation in Trichosanthes.