Abstract
Variation in flower size is an important aspect of a plant’s life history, yet few studies have shown how flower size varies with environmental conditions and to what extent foliar responses to the environment are correlated with flower size. The objectives of this study were to (1) develop a theoretical framework for linking flower size and leaf size to their costs and benefits, as assessed using foliar stable carbon isotope ratio (δ13C) under varying degrees of water limitation, and then (2) examine how variation in flower size within and among species growing along a naturally occurring moisture availability gradient correlates with variation in δ13C and leaf size. Five plant species were examined at three sites in Oregon. Intra- and inter-specific patterns of flower size in relation to moisture availability were the same: the ratios of the area of flower display to total leaf area and of individual flower area to leaf area were greater at sites with more soil moisture compared to those sites with less soil moisture. The increase in flower area per unit increase in leaf area was greater at sites with more soil moisture than at sites where water deficit can occur. Values of δ13C, an index of water-use efficiency, were greater for plants with larger floral size. The patterns we observed generalize across species, irrespective of overall plant morphology or pollination system. These correlations between flower size, moisture availability, and δ13C suggest that water loss from flowers can influence leaf responses to the environment, which in turn may indirectly mediate an effect on flower size.
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Acknowledgments
Thanks to B. Bond, J. Gaudinski, and P. Koch for use of lab equipment and facilities, to P. Brooks and S. Mambelli for technical assistance with our stable isotope analyses, and to D. Falster, D. Warton, and I. Wright for making (S)MATR available online. We also thank C. Galen whose valuable comments improved this manuscript. We gratefully acknowledge the Oregon State McDonald–Dunn Research Forest for permission to use the Forest Peak study site.
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Communicated by John Keeley.
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Lambrecht, S.C., Dawson, T.E. Correlated variation of floral and leaf traits along a moisture availability gradient. Oecologia 151, 574–583 (2007). https://doi.org/10.1007/s00442-006-0617-7
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DOI: https://doi.org/10.1007/s00442-006-0617-7