Ecophysiological implications of low lignin in eastern leatherwood (\u3ci\u3eDirca palustris\u3c/i\u3e L.)

Dirca palustris L. (eastern leatherwood) is an understory shrub found throughout much of eastern North America. Dirca palustris wood has a low concentration of lignin, which is a molecule that grants structural rigidity to cell walls. The branches of D. palustris are thus remarkably flexible, but their low lignin content could cause greater vulnerability to water stress. We examined the conductivity, vessel anatomy, and field water potential of D. palustris and conducted ecological surveys. The data showed that D. palustris was not experiencing substantial drought-induced dysfunction in the field, even during an exceptionally hot and dry summer. Its water potentials in the field were less negative than water potentials that caused substantial embolism in the lab, and it continued to photosynthesize and conduct water throughout the summer. We also found that D. palustris had small vessels, which may help it resist water stress. Ecological surveys showed that 15% of surveyed plants survived litterfall from canopy trees, almost all without damage, demonstrating a possible advantage of the low lignin content and flexible branches seen in D. palustris. These characteristics may allow D. palustris to continue to thrive in increasingly challenging environments brought on by climate change