Tubiform petal and its formation of Paeonia suffruticosa and P.lactiflora

The tubiform petal of Paeonia suffruticosa and P. lactiflora is a special petal which only has been occurred in the highflower of pralification flower in above two species. The petal is similar to corolla of some sympetalous dicotylodon family in shape, however it has a thinner base and different lobes in form and size. On base of the facts that all tubiform petals only form in the highflower of proliferation flower, the most highflower petals excluding the tubiform petal always occur the transforming development carpel-disc in the dorsal base, and there are special anatomy structures, a viewpoint that the tubiform petal comes from the petaloid developing of carpel and carpel-disc has been put forward. Furthermore, the jointly petaloid development process and feature of the tubiform petal have been described. Lastly the theory and practical signification of tubiform petal has been discussed.