Testing Carlquistian hypotheses on the functional significance of vessel element length

Summary While total vessel length is widely recognized as being of fundamental functional significance, opinion more divided regarding the potential importance element length, a variable that Sherwin Carlquist regarded functionally significant. We show can, predicted, affect resistance to deformation. Perforation plates are locally thickened annuli, so tubes with annuli resist deformation better than those without, and closely-spaced distantly spaced ones. However, there tradeoff between conductance. With comparative analysis across 1000 species angiosperms, we both areas individual inter-conduit pits scale positively diameter. Such covariation expected if plants maintain conductance they grow taller. Congruent Carlquist’s thinking, found elements exceptionally short tend in drylands, whereas long moist climates. Finally, evidence suggesting selection on an important determinant imperforate tracheary length. Conversely, for affecting appears be weaker. These results seem sufficient establish that, whatever significance its own right, congruent long-held views.