Stress-induced male sterility and mixed mating in the island plant Cedronella canariensis (Lamiaceae)

On the Canary Islands, we studied reproductive ecology of the perennial laurel forest herb Cedronella canariensis (Lamiaceae). Flowers contained small quantities of concentrated nectar. Flower visitors were mainly bumblebees (Bombus terrestris subsp. canariensis) and lepidopterans (especially Macroglossa stellatarum). Their abundance, pollen load, and behaviour are reported. Cedronella canariensis was facultatively autogamous. The P:O ratio was higher than expected for a plant with a breeding system of this nature. Seed set was not pollen-limited. Selfed and outcrossed seeds differed in weight. Small, lightly coloured flowers with dysfunctional stamens appeared towards the end of the season. This male-sterility might be induced by drought.