Data from: Reading the leaves: a comparison of leaf rank and automated areole measurement for quantifying aspects of leaf venation

The reticulate venation that is characteristic of a dicot leaf has excited
interest from systematists for more than a century, and from physiological
and developmental botanists for decades. The tools of digital image
acquisition and computer image analysis, however, are only now approaching
the sophistication needed to quantify aspects of the venation network
found in real leaves quickly, easily, accurately, and reliably enough to
produce biologically meaningful data. In this paper, we examine 120 leaves
distributed across vascular plants (representing 118 genera and 80
families) using two approaches: a semiquantitative scoring system called
“leaf ranking,” devised by the late Leo Hickey, and an automated
image-analysis protocol. In the process of comparing these approaches, we
review some methodological issues that arise in trying to quantify a vein
network, and discuss the strengths and weaknesses of automatic data
collection and human pattern recognition. We conclude that subjective leaf
rank provides a relatively consistent, semiquantitative measure of areole
size among other variables; that modal areole size is generally consistent
across large sections of a leaf lamina; and that both
approaches—semiquantitative, subjective scoring; and fully quantitative,
automated measurement—have appropriate places in the study of leaf
venation.