Characteristics of pollination biology of Melastoma affine

The flowering stage of Melastoma affine extends from the beginning of May to the end of June,and the opening period of single flower lasts one day.With heterostemony,five pieces of yellow anther lie above the stigma,and five pieces of mauve anther dividing into two parts lie below the stigma.The shape of the pollen grains is subspheroidal,and they are 6-lobed circular in polar morphology.3 pseudo-colporates of the pollens with yellow anthers connect the two poles,while the other 3 pseudo-colporates with mauve anthers do not.Different pollen viability exists between the yellow anthers and the mauve ones,and the differences decrease with the development of flowers.The number of seeds in per fruit with cross-pollination is obviously higher than that of the self-pollination.As for the two kinds of pollination,the effect on pollination with yellow anthers is better than that with mauve anthers.The pollination insects include Bombus sapporensis,Bombus ignites,Amegilla calceifera and so on.The frequency of the pollination insects visiting the flowers is highest from 9:30-10:30 a.m.per day,and there are no visitors after 11:40 a.m.The outcrossing index is 4.The breeding system is partially self-compatible,while the outcrossing demands pollinators.The ratio of pollen and ovule is 601.54,and the breeding system belongs to compatible outcrossing.