Reproductive biology of Chinese herbaceous perennial Peony (Paeonia lactiflora Pall.) using the Paraffin Method

Chinese herbaceous peony (Paeonia lactiflora Pall.) is a popular ornamental plant. However, little is known about its reproductive biology by histological analyses. Here, we used the paraffin wax method to study the reproductive biology of the Chinese herbaceous peony (Paeonia lactiflora 'Dafugui'). The results showed that the flower bud of Chinese herbaceous peony was a mixed bud. The course of flower bud differentiation included some developmental morphology periods, such as bract, calyx, petal, stamen, and pistil. The anther wall development was related to a dicotyledonous type. Pollen was mainly 2-celled, only few of them were 3-celled. Moreover, the mature pollen was circular with three germinal apertures. The number of pollen in petaloid anther was less than normal with different maturation periods. Superior ovary, polymerized follicle, anatropous ovule, polygonum type embryo sac, and serious embryo sac abortion were the features of the Chinese herbaceous peony found in this study. Moreover, in the Chinese herbaceous peony, the embryo was of a dicotyledonous type; the endosperm followed a nucleus model, and the seed coat showed double wall.