Vessel scaling in evergreen angiosperm leaves conforms with Murray's law and area‐filling assumptions: implications for plant size, leaf size and cold tolerance

What is it about?

It is predicted from theory that the thickness and number of vessels (water-transporting “pipes” in flowering plants) in plant tissues should correlate to one another (i.e., “scale” with one another) in a way that results in maximal conductance of the entire vessel network. It is also predicted that we might expect shifts in vessel scaling across aridity and temperature gradients. We measured the change in vessel width and number in the leaves of 36 species spanning a large range in aridity and temperature in eastern Australia, and evaluate the degree of divergence in vessel scaling across these species and habitats. The scaling of vessel width and number did not differ across species and habitats, and did not differ from that predicted from maximal conductance theory (Murray’s law). Leaf size was strongly correlated with the thickness of vessels and did not differ among habitats, nor did the scaling differ significantly from that predicted from Murray’s law. The thickness of vessels in leaves was related to the temperature of a species’ habitat and suggests that temperature sets a limit on the maximum thickness of vessels (and therefore the achievable plant/leaf size) in a given habitat.

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