Vessel diameter polymorphism determines vulnerability-to-embolism curve shape

Summary Sherwin Carlquist proposed several functional interpretations for vessel diameter, including that narrow vessels were hydraulically “safe” while wide diameter more vulnerable to embolism. He applied these ideas both across species and biomes, within xylem tissue, where function of growth ring types was inferred from polymorphisms (occurrence differing classes a tissue). Following on Carlquist’s ideas, we interested in evaluating if polymorphism could be linked vulnerability-to-embolism curve shape. Vulnerability curves fit with model included continuous shape term (alpha). We predicted high variation would result lower alpha (more r-shaped) whereas low produce higher s-shaped) curves, potential intermediate types. Our findings support diameter. Vessel strongly correlated vulnerability Homogeneous diameters associated s-shaped curves. As increased, declined became linear. High r-shaped There no relationship between length common estimate embolism resistance (P50), wider increased vulnerability. show enormous variety scale, parameters are likely critical understanding predicting plant function. ecological anatomy data, predictions, inferences will continue valuable as expand our structure–function links anatomy.