Studies on the factors that restrict sexual reproduction and fruit setting in Memecylon flavescens – an endangered taxon

Abstract

Memecylon flavescens Gamble is an endangered taxon of Nilgiri region of Western Ghats. Extensive survey in the study area- Avalanche, Ooty made during 2015-18 has revealed a few interesting aspects about the sexual reproductive cycle. Fruit setting is substantially very low though profuse flowering occurs. Flowers are hermaphrodite, actinomorphic, tetramerous, pin type and protogynous, favouring cross-pollination. Pollen fertility as assessed by Alexander’s differential staining is about 30%. Sections of flower buds have revealed the infestation by undescribed gallmidge (Diptera: Cecidomyiidae). In 90% of the flower buds observed, gall midge galleries are seen at various levels in the flower bud, destroying the reproductive organs by larval feeding. Hence, negligible fruit setting is mainly due to gallmidge infestation. Protogynous nature and low percent of pollen fertility are added factors aggravating the effect on fruit setting.