Dr. Craig Martin studies the biochemical, physiological, anatomical, and morphological responses of plants to stressful environments.
Much of my labs' effort is focused on the ecophysiology of plants having different photosynthetic pathways, e.g., Crassulacean acid metabolism (CAM), C4, and C3. In addition, we are interested in the potential ecophysiological significance of variations or intermediacy in these pathways, including CAM-cycling, C3-CAM intermediacy, and C4-CAM intermediacy. Recent projects receiving attention in the lab include the following: ecophysiological consequences of soil burial in species of Lithops, or "living stones," potential water conservation associated with CAM-cycling in succulents growing on rock outcrops in the Midwest, the multiple mechanisms underlying high water-use efficiency in CAM plants, the potential effect of nocturnal malic acid accumulation on the water relations of CAM plants, the importance of C4 taxa during old-field succession in the Midwest, ecophysiology of several C4 prairie grasses relative to their microclimate, and the evolution of CAM in a diverse array of vascular plants.
Another emphasis of our research efforts centers on an elucidation of the physiological and morphological adaptations of plants to the epiphytic habitat in the tropics and subtropics. Most of this research features epiphytic bromeliads, especially members of the genus Tillandsia, many of which are CAM plants. We are interested in learning how such plants survive the aerial or arboreal environment while lacking functional roots, often lacking an ability to store substantial amounts of water, and facing scarce elemental nutrient availability. Specific research projects have included studies of shade adaptations in epiphytic bromeliads, adaptations and responses to drought stress in these plants, the impact of CAM on the water relations of such epiphytes, and the effects of dense epidermal trichome cover on gas exchange in atmospheric species of Tillandsia.
Not all the research in my lab is limited to CAM plants and epiphytic bromeliads. We pursue any questions about the ecological aspects of physiological and morphological adaptations of plants to stress. Such studies include comparisons of the water relations of different types of prairie plants, investigations of the degree of competitive interactions among weeds and prairie plants, sun/shade adaptations in mosses and grasses, effects of leaf age on photosynthesis and transpiration in tropical trees, the potential importance of water movement between leaves during drought stress, effects of space exposure on seed and seedling vigor, and effects of atmospheric pollutants on the ecophysiology of trees and crop plants.
By the way, the bizarre plant next to me in the above photograph is Welwitschia mirabilis, endemic to the Namib Desert in Namibia. This unusual plant, despite its appearance, has only two leaves, and is related to gymnosperms. It was originally reported to be a CAM plant, then the initial evidence was refuted, but a recent report indicates that these odd plants can indeed engage, to some degree, in CAM photosynthesis. Regardless, its physiology, as well as its appearance and evolutionary history, remain intriguing.