兰科（Orchidaceae）植物具有极高的观赏和药用价值，也是重要的保护类群。水分供需平衡机制的阐明对兰科植物多样性维持和演化具有重要意义，但兰科植物尤其是附生种的水分生理生态机制仍不清楚。前人的研究主要集中于兰科植物叶片的水分关系与生态意义，鉴于花作为被子植物的繁殖器官，并且对其后代繁衍具有重要影响，但关于花的水分利用特征及对干旱胁迫的响应却知之甚少。因此，本项目以花为研究对象，运用生理学、形态学和系统发育学等多学科交叉的研究方法，通过对地生兰和附生兰花的结构与功能性状进行比较，重点研究：（1）地生兰和附生兰花的形态结构差异与生境的关系；（2）花的水力结构特征与抗气穴化能力的内在联系；（3）不同生境中兰科植物的花、叶和根间的功能协调。研究结果以期揭示兰科植物花的水分利用特征及对干旱胁迫响应的生理机制，为兰科植物多样性维持和演化提供新的思路和视角，同时为其种质资源的保护利用提供科学依据。

Orchidaceae is an important ornamental and medicinal plant, as well as an important conservation group. The understand of mechanism of water supply and demand balance maintenance is of great significance to the maintenance and evolution of diversity in Orchidaceae, but the water physiological and ecological mechanism of orchid species, especially epiphytic orchids, is still unclear. Previous studies mainly focused on the water relationship and ecological significance of leaves in Orchidaceae. Flowers are the sexual reproductive organs of flowering plants, which have an important impact on the reproduction of plant offspring. However, but little is known about the water use characteristics of orchid flowers and their response to drought stress. Therefore, this project will focus on flowers, the structure and functional characteristics of epiphytic orchids and terrestrial orchids will be comparatively researched by integrating physiological, morphological and phylogenetically independent contrast approaches. The main research contents include: (1) the difference of morphological structure and functional traits between terrestrial orchids and epiphytic orchids and their relationship with habitats; (2) the intrinsic relationship between the hydraulic structure characteristics of flowers and the ability of resistance cavitation. (3) the functional integrations among flower, leaf and root when the orchid plants are exposed to environmental stresses. This project will address the water use characteristics of flowers and their response to drought stress in Orchidaceae. The outputs will provide new ideas and insights for the occurrence, maintenance and evolution of diversity in Orchidaceae, and provide novel knowledge on the conservation and utilization of species resources in Orchidaceae.