Cypripedium subtropicum is the only known perennial evergreen herb in Cypripedium of Orchi-daceae.Its wild resources have been severely damaged,and the number of wild populations has decreased dra-matically.It has been listed as a first-class protected wild plant in China.In order to explore the differences in anatomical structure and photosynthetic physiological characteristics of leaves at different growth stages of C.subtropicum,the leaf epidermal characteristics,leaf anatomical structure,photosynthetic characteristics and photosynthetic pigment content were studied in this study.It was prospected to provide scientific basis for the conservation,introduction and domestication of C.subtropicum.The results showed that:(1)The shape of the upper and lower epidermis of C.subtropicum leaves was irregular and wavy,and the stomata and epidermal hairs were only distributed in the lower epidermis.The leaf structure was composed of epidermis,mesophyll and veins,and the mesophyll had no differentiation of palisade tissue and spongy tissue.The stom-atal area,leaf thickness and leaf main vein thickness of fruiting plants were significantly larger than those of the seedlings.(2)The maximum net photosynthetic rate(Pmax),Light Compensation Point(LCP)and Ap-parent Quantum Efficiency(AQY)of fruiting plants and seedlings were lower,and fruiting plants were sig-nificantly higher than the seedlings,indicating that it had the characteristics of shade plants.(3)The photo-synthetic pigment content of leaves from fruiting plants was significantly higher than that of the seedlings.(4)The Pmax,LSP,AQY,Rd of C.subtropicum leaves were significantly correlated with both Chl(a+b)and leaf main vein thickness.C.subtropicum is a typical shade plant.Its range of light adaptation and its ability to utilize light energy are relatively low.Furthermore,the photosynthetic capacity of fruiting plants is stronger than that of seedlings.Therefore,it is necessary to shade the seedlings to a higher degree during the introduc-tion and domestication process.
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