This chapter mainly considers areas of major ignorance to which allometric arguments might make a valuable contribution. Possible shortcomings of the allometric approach used throughout this book are also voiced.

Allometry in plants

With a few notable exceptions, remarkably little work has been done on the allometry of plant growth and reproduction. Despite some early allometric approaches (Pearsall, 1927; Turrell, 1961) more recent papers and books on these topics (e.g. Hunt & Parsons, 1974; Hurd, 1977; Hunt, 1978; Venus & Causton, 1979) fail to include allometric analyses and instead abound with detailed calculations of plant growth curves, in particular; yet the plethora of equations and statistical techniques used fail to provide a functional framework within which to consider plant growth and reproduction.

A first approach would be to see whether the allometric growth equation of Chapter 5, Equation (5.4), provides a useful fit to plant growth curves.

A very great deal more could also be done on the allometry of plant reproduction along the lines of Whittaker & Woodwell (1968) and Hubbell (1980). Hubbell found that a doubling of circumference in the tropical tree Bursera simaruba produced nearly a 50-fold increase in mean seed crop (cf. Chapter 4). Such studies, whether intraspecific or interspecific, are easy and relatively quick to carry out, produce invaluable data and may be of commercial value too.

Optimal organ size

As one might expect, the weights of many organs scale both intraspecifically and interspecifically on body weight with exponents of close to one. There are, however, some interesting and notable exceptions.