Pollen limitation in Eremostachys superba Royle ex Benth. (Labiatae) and its role in loss of seed production

Abstract

The critically endangered Eremostachys superba Royle ex Benth. Shows almost negligible sexual reproduction under natural conditions (<= 5%) and survives only vegetatively. Investigations on the role of pollination biology in the loss of sexual reproduction revealed a pollinator limitation in the natural habitat. Increased floral attractiveness was provided to counteract this pollinator limitation syndrome by increasing flower density. Observations were made on insect visits and resultant seed set in the ex situ plants and compared with that observed under in situ conditions. Infinite pollinators visited ex situ flowers but affected only 38% seed set, indicating a reduced fertilization due to geitonogamous pollination. These results suggested that lack of sexual reproduction in E. superba was partly due to pollen limitation.