Leaf physiological and anatomical responses of two sympatric species to temperature.

and are two endangered orchid species, with high ornamental and conservation values. They are sympatric species, but their leaf anatomical traits and flowering period have significant differences. However, it is unclear whether the differences in leaf structure of the two species will affect their adaptabilities to temperature. Here, we investigated the leaf photosynthetic, anatomical, and flowering traits of these two species at three sites with different temperatures (Kunming, 16.7 ± 0.2 °C; Puer, 17.7 ± 0.2 °C; Menglun, 23.3 ± 0.2 °C) in southwest China. Compared with those at Puer and Kunming, the values of light-saturated photosynthetic rate (P), stomatal conductance (g), leaf thickness (LT), and stomatal density (SD) in both species were lower at Menglun. The values of P, g, LT, adaxial cuticle thickness (CT) and SD in were higher than those of at the three sites. Compared with , there were no flowering plants of at Menglun. These results indicated that both species were less resistance to high temperature, and had a stronger adaptability to high-temperature than . Our findings can provide valuable information for the conservation and cultivation of species.