Abstract Detail

Anatomy and Morphology

Ray, Dustin [1], Jones, Cynthia [2].

Mechanical and physiological traits do not trade off in petioles.

Petioles bridge the stem and leaf lamina, so they are essential for the conduction of photoassimilates and water within plant vascular tissues. Since petioles must be flexible enough to bend and twist in the wind without breaking, petiole cross-sectional area could be limited, resulting in a tradeoff between vascular tissues and supporting tissues within the cross-section. Our previous anatomical research suggests however, that in the South African genus Pelargonium L'Hér, there is ample space for both vascular tissue and supporting tissue within the petiole cross-section. To better understand the relationships between mechanics, physiology and anatomy within the petiole, we measured petiole mechanical traits, anatomical traits, and whole leaf physiological traits (maximum photosynthesis, stomatal conductance, petiole sap flow velocities). From this data, we created piecewise structural equation models to determine the possible relationships of structural predictors with mechanical and physiological traits as response variables. Our models suggest that there is little overlap in the traits that predict mechanical and physiological traits. Mechanical traits were generally predicted by petiole size or lamina mass and related traits, while physiological traits were predicted by traits related to lamina area and petiole hydraulics (xylem area, hydraulic mean diameter). We propose that the absence of overlapping predictors for physiological and mechanical response variables provides further evidence that mechanical requirements are not constraining the petiole hydraulic traits within Pelargonium petioles.

1 - University of Connecticut, Department of Ecology and Evolutionary Biology, 75 N Eagleville Road Unit 3043, Storrs, CT, 06269, USA
2 - University Of Connecticut, Department Of Ecology & Evolutionary Biology, Unit 3043, 75 N. Eagleville Rd., Storrs, CT, 06269, United States

Keywords:
Pelargonium
petiole
Leaf anatomy
functional anatomy
biomechanics.

Presentation Type: Oral Paper
Session: 6, Anatomy and Morphology I
Location: 113/Mayo Civic Center
Date: Monday, July 23rd, 2018
Time: 8:30 AM
Number: 6003
Abstract ID:635
Candidate for Awards:Katherine Esau Award