Pollination Biology Of Calanthe Alismaefolia

As a very evolutionary taxa of angiosperms, the structure of orchid flowers and pollinator were highly adapted.In this paper, combination of field observations and laboratory experiments, as well as scanning electron microscopy and other experimental method, we studyed the pollination biology of Calanthe alismaefolia. This paper mainly discusses the C. alismaefolia floral characteristics and pollinators adaptability, as well as the driving role of pollinators in the evolution of floral character, would expect from the perspective of pollination and reproduction for C. alismaefolia to provide a reasonable protection and management strategies, which the main results are as follows:1. Floral traits of C. alismaefoliaC. alismaefolia blossoms from May to July with3-10branches in racemes, and it has a high density of flowers, the process of flower anthesis last about7-10days. The entire flower is bilaterally symmetrical. When the flower is completely open, the labellum extend horizontally. Stigma and labellum are white, the base of the labellum has a yellow corpus callosum, and stigma is located in the anther cap on both sides, with spur but no nectar.2. Pollinators and attract insects mechanismOur observations showed that Choaspes hemixanthus and Celaenorrhinus oscula are the pollinator. They all belong to the Lepidoptera family and Hesperiidae genus. C. alismaefolia maybe attracted the pollinator through the yellow corpus callosum、 spur and the large flower show, this pollination mechanism belongs to the generalized food deception pollination.3. Blossom biology characteristicThe pollen of C. alismaefolia is starchless. The number of pollen grains and ovules per flower is averaging1027289.7±11411.1and36540.5±7043.5. The Pollen-ovule ratio (P/O)and Ovule-seed ratio (O/S) are28.53±2.73and1.048respectively. Respectively using peroxidase solution and benzidine-H2O2method, we measured the pollen viability and stigma receptivity in the period of budbloom time, early bloom time, full bloom time and wither bloom time. The pollen viability of C. alismaefolia with time prolonging first increased and then decreased, the period of the early bloom was higher than that in other three periods. The stigma receptivity varied in different stages change as time increases, from initially a part of the activity to the last complete loss of activity.4. Types of breeding systemsField observation found the passive selfing phenomena exist in C. alismaefolia. The fruit set rate under natural condition was23.3%. The fruit set rate of induced autogamy、hand geitonogamy and Cross-pollination was100%, these results indicate that C. alismaefolia is highly self-compatible. Emasculation bagging and not emasculation bagging are not fruitful, these results show that there is no spontaneous autogamy and apomixis. So it must depend on insects for successful reproduction under the natural condition. The difference of seed vigor of artificial pollination was not significant. It showed that C. alismaefolia don’t have inbreeding phenomena, and the seed vigor is not the main factors of which restricted to seed germination and population expansion of C. alismaefolia.