Photosynthesis is one of the most fundamental and broadly recognized aspects of a plant’s biology. Despite what we learn (and, perhaps, teach), photosynthesis is wonderfully varied and adaptable, evolving over time to maximize plant growth under varying conditions. For example, Crassulacean acid metabolism (CAM) is a modification to the standard C3 photosynthetic pathway that concentrates carbon around RuBisCO and allows for efficient CO2 fixation under conditions that might otherwise be detrimental to carbon gain, like water limited environments. And because CAM plants conduct the majority of their gas exchange at night, when temperatures are cooler, they are some of the most water-use efficient species on the planet. It’s no surprise that many CAM plants therefore inhabit dry ecosystems like deserts, as well as seasonally dry tropical forests and epiphytic habitats, where water is limited. CAM photosynthesis has over 80 independent origins in land plants, yet how CAM evolves from a C3 ancestor is still not clearly understood. The Agavoideae (Asparagaceae) have emerged as a model clade for understanding the evolutionary progression from C3 to CAM. In particular, the variable ways species within the Agavoideae employ CAM photosynthesis makes the subfamily particularly well suited for comparative studies. My previous work in this system has taken an interdisciplinary approach to understand CAM at the whole organism level, from ecophysiology to anatomy and evolutionary genetics. Here, I will highlight how the Agavoideae has enabled new ideas and hypotheses for the evolution of CAM photosynthesis, and how new work is paving the way for comparative genomics to deepen our understanding of the evolution of this complex trait.