Developmental and Structural Section
Chu, Elaine , Walls, Ramona L. .
Significant correlation between xylem element diameter and leaf size within and across taxa.
The aim of this study was to test the hypothesis that within the same genus, xylem element diameter increases in the mid-rib with the leaf size, but that this relationship will not hold up across distantly related genera. To test the relationship between vessel size and leaf size, we cut hand sections of the midrib of six to ten species from six genera and measured xylem element cross-sectional area. We used scanned images of fresh leaves to measure leaf size. There were significant relationships between leaf area and xylem element size within each taxon, supporting the first part of our hypothesis. There was also a significant relationship across all taxa, contradicting the second part of our hypothesis. The failure to find a relationship between mid-rib xylem element size and leaf size across distantly related species in earlier studies may have been due to limited sample size. Therefore, we tested whether or not our results depended on having a large sample, by randomly selecting sets of 10 species and testing for a relationship between mid-rib xylem element size and leaf size. The relationship between leaf size and xylem element size across taxa appears to depend on having a sufficient sample size, since random samples of only ten species had highly variable regression coefficients. Out of fifty random samples, 68 % had a significant relationship. This suggests that the observed relationship across different genera it is strongly related with the variety of species and the amount of data being studied. Therefore, our results suggest that it is reasonable to assume that xylem element diameter will increase in the mid-rib with the leaf size, even across genera.
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1 - Stony Brook University, Ecology and Evolution, 650 Life Sciences Bldg, Stony Brook , NY, 11794, USA
2 - New York Botanical Garden, Bronx, NY, USA
Presentation Type: Poster:Posters for Sections
Location: Hall A/Convention Center
Date: Monday, August 2nd, 2010
Time: 5:30 PM