A Study On Reproductive Behaviour In Aquilegia Yabeana

Because of a sessile lifestyle combined with unstable pollination environments, different flowering plants often exhibit various reproductive strategies. We made observations and study in the morphology, development and behaviour of the male and female reproductive organs of a perennial herb, Aquilegia yabeana to understand its pollination mechanisms and reproductive strategy under fluctuating pollination environments. Investigations were conducted in the natural population and artificial population of this species. Main results are as the following:1. Characters of stigma in the genus of Aquilegia are unusual. The stigma is not confined to the tip of the style but extensive down the style base along ventral slit. During anthesis papillae stigma surface develop and present gradually from the style tip down to its base, with the receptive area enlarging. Such a developmental pattern is entitled to continous renewal of receptive surface and may enhance female reproductive success by the prolongation of stigma receptivity.2. Sequentially blooming flowers on the individual of A. yabeana varied their temporal floral allocations significantly with ovule number stable but pollen production decreased gradually making a female-biased sex allocation. This trait could be under the selection of the changing pollination environments caused by protogyny.3. The stigma development of A. yabeana was plastic and independent of one another within the same flower. Pollination can arrest the further development of stigma tissue, with the regulating role pronounced at the beginning of anthesis, decreased rapidly during early anthesis and faded out in mid anthesis. The arrest of further stigma development must contribute to the resource transmission and late steps of reproductive success. It is the first report of plasticity in stigma development.4. Flowers of A. yabeana can self-pollinate autonomously, which occurs in middle of stigma receptive period. Autonomous self-pollination did not prohibit later potentialpollination mediated by pollinators. Moreover, the latter was endowed with positional advantage and possibilities of reproductive success. Compared to later arriving pollen autonomous selfing had the head start in pollination but fertilization was delayed, making a new regulation of post-pollination pollen competition.Altogether, the reproductive behaviour of A. yabeana was flexible with respect to pollination environments, expressing a strategy to assure and optimize reproduction.