EVIDENCE THAT TEMPERATE EAST NORTH AMERICAN EVERGREEN WOODY PLANTS FOLLOW CORNER'S RULES

Abstract

Coener's rules, first developed for tropical trees, predict a spectrum of woody plant forms, from ones with small leaves, thin twigs (first‐year shoots) and many branches, to ones with larger Waves, thick twigs and few branches. These rules were confirmed for nine broad‐leaved and 12 needle‐leaved evergreen woody plants of temperate eastern North America: for each of these groups, leaf size was positively correlated with twig cross‐sectional area and both of these were negatively correlated with the number of twigs needed to bear 104 cm2 total leaf area. When compared to deciduous trees, characterized in a previous study, broad‐leaved evergreens had leaves that were 85% smaller at a given twig thickness and needed 750% more twigs to bear a given total leaf area (at least when leaves older than 1 year were ignored). Needle‐leaved evergreens bore relatively small leaves but large numbers of leaves per first‐year shoot; they bore fewer twigs per 104 cm2 total leaf area than broad‐leaved evergreens, but more than broad‐leaved deciduous species. Broad‐leaved deciduous trees were characterized by relatively large leaf sizes as a function of twig cross‐sectional area and low numbers of twigs per 104 cm2 total leaf area. Although Corner's rules are a significant index of plant form, a full resolution of the differences between deciduous and evergreen species awaits further study. Copyright © 1983, Wiley Blackwell. All rights reserved