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Our study investigated key parameters, such as leaf thickness, stable carbon isotope discrimination (δ13C), diurnal net CO2 uptake dynamics, and titratable acidity content. These analyses aimed to enhance the scientific and efficient breeding and cultivation management of these species. These analyses aimed to explore the responses of photosynthetic carbon assimilation pathways of these two species to drought stress. Our findings indicated that Angraecum sesquipedale had a leaf thickness of 1.07 mm and a 8°C value of 17.24%e, while for A. sororium, the values were 0.58 mm and 27.74%, respectively. A. sesquipedale predominantly absorbed CO2 during the night period, and its net CO2 uptake rate gradually decreased with increasing drought stress. In contrast, A. sororium primarily absorbed CO2 during the light period under non-drought conditions, whereas its night period net CO2 uptake rate turned positive and steadily increased after 2-5 days of drought treatment. The disparity in titratable acidity content between dawn and dusk in A. sesquipedale decreased from 47 mmol.g-1 under non-drought conditions to 22 mmol.g-1 under drought stress. Conversely, it increased from 39 mmol g-1 to 60 mmol g-1 in A. sororium. The results supported the classification of A. sesquipedale as a crassulacean acid metabolism (CAM) plant, while A. sororium exhibited characteristics of a C3 plant with some CAM features. Remarkably, the activation of the CAM pathway in A. sesquipedale seemed unaffected by drought stress, unlike A. sororium, where drought stress appeared to trigger this metabolic shift. [ABSTRACT FROM AUTHOR]