PARENT SESSION
Contributed Oral Session 123: Photosynthesis and Water Relations: Leaf Architecture
Thursday, August 11, 8:00 AM - 11:30 AM, Meeting Room 522 A, Level 5, Palais des congrès de Montréal
Palmate versus pinnate leaf venation systems: Do they diverge in function?
Sack, Lawren*,1, 2, Dietrich, Elizabeth2, Sanchez, David3, Streeter, Christopher2, Holbrook, N. Michele4, 1 Department of Botany, University of Hawai'i, Honolulu, Hawai'i, USA2 Harvard Forest, Petersham, Massachusetts, USA3 Centro de Ciencias Medioambientales, Madrid, Spain4 Department of Organismic and Evolutionary Biology, Cambridge, Massachusetts, USA
ABSTRACT- Leaves of dicotyledons vary tremendously in their venation architecture, but little is known of the potential functional consequences. One striking dichotomy is between palmate and pinnate arrangement of major veins. We applied cutting treatments to the veins of leaves on naturally occurring trees of temperate woody angiosperms, for species with pinnately- or palmately-veined leaves. Once the leaves had healed the wounds, we measured performance, relative to control leaves, in leaf hydraulic conductance, in stomatal conductance and in parameters of chlorophyll fluorescence, as an index of photosynthetic function. Preliminary analyses indicate that pinnately-veined leaves were inherently more sensitive to damage: severing the primary vein dramatically reduced leaf function. By contrast, in palmately-veined leaves, severing the central primary vein reduced function much less strongly, especially further from the cut, with the surrounding primary veins compensating for the loss of water supply capacity. Functional differences among leaves of contrasting vascular design have implications for leaf evolution, ecology and biogeography.
Key words: biological networks, leaf hydraulics, herbivory, hydraulic architecture