Abstract: In this study，the morphological characters of petals from stamen primordia in Paeonia suffruticosa，P.rockii，P.ludlowii，P.decomposita, P.ostii，P.qiui，P.delavayi and P.lactiflora have carefully been surveyed． Furthermore，the quantity of tubiform petals from stamen primordia only occurred in P. suffruticosa，P. rockii and P.lactiflora have been measured，and their anatomic construction have been examined．The results as following：(1) The rate of tubiform petals from stamen primordia is quite low and its morphological characters is simple in the flowers of P.suffruticosa and P.rockii. By contrast，the rate of tubiform petals from stamen primordia is obviously higher and its morphological characters is more complex in the flowers of P.lactiflora．(2) From bottom to top, there is a series of transformation in the anatomic construction of tubiform petals from stamen primordia．In contrast to the anatomic construction of tubiform petals from stamen primordia in P.suffruticosa and P.rockii, P. lactiflorasis more diverse. (3) Sustained differentiation of the lateral meristem of the vascular bundle and the increase of the quantity of vascular bundle play a key role during the developmental process transformed the stamen primordium into tubiform petal. (4) The developmental process of the tubiform petal from stamen primordium can be divided into following four stages, the primordium differentiation，the transformation development，the formation of tubiform petal and the maturation of tubiform petal.

Key words: Paeonia, P. suffruticosa, P.lactiflora, Stamen primordium, Tubiform petal, Developmental process