Abstract:In order to understand the internal causes of endangerment of Michelia shiluensis, the morphological characteristics of flower organs, flowering dynamics and visiting insects were observed, and the pollen germination rate, stigma acceptability and breeding system characteristics were tested. The results showed that the stamen group and pistil group naturally form spatial isolation during flowering, and the perianth plate bends laterally to form a spherical space to protect the stamen group. The pistil stalk continues to extend, pushing the pistil out of the stamen and perianth. The main flower-visiting and pollinating insect of the nurseries are Apis mellifera. Stigma acceptability was strongest in stages VI and VII when the perianth was open to 50% of the maximum diameter. The pollen activity of stage VI was also the highest, and the germination rate in vitro was (66.96±11.28)%. The same flower or cross-flower pollination of the same plant could not bear fruit, but the fruit rate of cross-pollination was 100%. Therefore, Michelia shiluensis is a strictly hetero-pollinated plant, with outbreeding and self-incompatibility, and there is no apomixes, and there is also reproductive isolation with other species of Michelia. The dynamic changes in perianth and pistillation groups of M. shiluensis revealed the biological mechanism of cleverly avoiding self-mating.
