Age-determination of Dicotyledonous Herbaceous Perennials by Means of Annual Rings: Exception or Rule?

Thirty-five herbaceous dicotyledonous perennial plant species, with permanent root systems, from 16 families, were examined for the presence of growth rings in the secondary root xylem. Most of the species surveyed showed ring zonations in the roots, and these could be verified as annual growth rings in the ten species for which plants of known age were available. The potential value of ‘herbchronology’ as a tool in ecological investigations of species and stands of perennial herbs of temperate zones is discussed.