Scaling relations for a functionally two‐dimensional plant: Chamaesyce setiloba (Euphorbiaceae)

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Abstract
Many characteristics of plants and animals scale with body size as described by allometric equations of the form Y = β M α , where Y is an attribute of the organism, β is a coeffi cient that varies with attribute, M is a measure of organism size, and α is an- other constant, the scaling exponent. In current models, the frequently observed quarter-power scaling exponents are hypothesized to be due to fractal-like structures. However, not all plants or animals conform to the assumptions of these models. Therefore, they might be expected to have different scaling relations. We studied one such plant, Chamaesyce setiloba , a prostrate annual herb that grows to functionally fi ll a two-dimensional space. Number of leaves scaled slightly less than isometrically with total aboveground plant mass ( α ≈ 0.9) and substantially less than isometrically with dry total stem mass ( α = 0.82), showing reduced allocation to leaf as opposed to stem tissue with increasing plant size. Additionally, scalings of the lengths and radii of parent and daughter branches differed from those predicted for three-dimensional trees and shrubs. Unlike plants with typical three-dimensional archi- tectures, C. setiloba has distinctive scaling relations associated with its particular prostrate herbaceous growth form.
Funding Information
  • National Science Foundation (PHY 0202180, 0353791)