Abstract [Objective] We aim to investigate the morphological adaptation characteristics of peony in different
habitats to the environment in the plain areas, and to provide references for peony conservation research
and screening of high-quality germplasm resources. [Methods] The Central Plain peonies (Paeonia
ostii ‘Fengdan’ and P .‘Luoyanghong’) and wild peonies (P . delavayi Franch, P . potanini, P . ludlowii,
P . lutea (Tibet), P . lutea and P . qiui) were used as materials, and paraffin section technique
was used to observe the leaf structure and analyze the related indexes. [Results] (1) The leaf epidermal
morphology of the Central Plain peonies and wild peonies showed varying degrees of variation. The leaves
were heterofacial, with the upper and lower epidermal cells were irregularly shaped, and the stomata was
uniformly distributed in the lower epidermis. (2) The leaves and cuticles of P . ludlowii were thin. The
palisade tissue was underdeveloped. The intercellular space was large and the stomatal density was high.
The thickness of leaves, palisade tissue, and sponge tissue of P . lutea was the largest. (3) Stomatal density
and epidermal thickness, chlorophyll b and chlorophyll a/b, total chlorophyll and chlorophyll a/b
were significantly negatively correlated (P <0.01). Stomatal index is positively correlated with palisade
tissue thickness, palisade tissue thickness and leaf thickness, chlorophyll b and total chlorophyll.
[Conclusion] The wild peony germplasms except P . ludlowii have strong adaptability to the plain habitats,
and the wet structure of P . ludlowii is the main reason why it cannot be cultivated in the plain area
