Mentor: Stephen D. Davis
In angiosperms and gymnosperms, mechanically strong leaves are positively correlated with dehydration-tolerance. In general, leaves that are stronger mechanically tend to be evergreen while those that are not are usually mechanically weak and deciduous in response to water stress. Avoiding water stress, especially in a chaparral Mediterranean-type climate, which receives less than 500 mm of water per year, requires energy-intensive adaptation. Ferns residing in the chaparral are presumed to adopt a similar strategy: either they maintain or abscise their pinnae in drought. It was reasoned that ferns with lower water potential and able to survive in drier conditions should be mechanically stronger than those in a mesic environment. Twelve species were collected from mesic and xeric regions in California. Tissue water relations, assessed by pressure-volume curves, were compared with pinna strength and vein density to identify adaptation to water stress. We hypothesize that dehydration-tolerance is positively correlated with mechanical strength as seen in angiosperms and gymnosperms.
Gillespie, Breahna, "Leaf Mechanical Strength Corresponds to Water Relations in Twelve Species of California Ferns" (2013). Pepperdine University, All Undergraduate Student Research. Paper 56.