Fundamentals of Dendrology Prepared By: David Mercker Extension Associate University of Tennessee Department of Forestry, Wildlife, Fisheries

Dendrology = That field of botany dealing with the identification/classification of trees and shrubs What tree is this? (den•drol´• •jē) e

process of elimination. Using a dicotomous key, Proper tree identification is a process of elimination. Using a dicotomous key, a series of if – then questions are asked, which carries the reader to the next series of questions. In a broad sense, trees can first be broken into group A or group B.

Group A Coniferous, Evergreens, Softwoods Green leaves present during winter Have either needles or scales Trees that bare cones: Pines, Spruces, Firs, Henlock

Group B Deciduous, Broad -leaves, Hardwoods Green leaves absent in winter Provide most of fall color Exception – Bold Cypress is an example of a “deciduous Conifer”

Needles Single Bundles Single = firs, spruce Bundles = pines Needles are bound together in a “fasicle” and identification is determined by the # of needles per fasicle.

Arrangement Group B Node = the point at which the leaf petiole attaches to the stem. Petiole = Leaf Stalk.

Types Simple Singular leaf with one petiole attaching to twig. Compound Several smaller “leaflets” each attached to a petiole which is then attached to a twig

Types = Simple One leaf, attached to one petiole, attached to the stem

Types Compound = How many leaves are in this picture? The peticle is very long; leaflets are without stalks and their base is directly attached to peticle. All portions break off together and fall to the earth in Autumn. How many leaves are in this picture?

Shapes Lobed Entire Southern Magnolia The Southern Magnolia is an example of a “simple and entire leaf.” Southern Magnolia

Leaf Margins Cottonwood Serrated Yellow Poplar Smooth Serrations can be tiny or large, pointed or hooked and sometimes doubly-serrated (serrations on serrations). Is the yellow poplar lobed or entire? Cottonwood Serrated Yellow Poplar Smooth

Sinus - Scarlet oak has deep sinuses Northern red oak has shallow sinuses Sinus = an indentation that protrudes inward on a leaf toward the midrib (vein) Sinus depth is particularly important for identifying oak species

(opposite sides proportional) Leaf Base Symmetry Symmetrical (opposite sides proportional) Asymmetrical (not proportional)

Bristle – Tipped Lobes Lobes with Bristles Lobes Smooth A characteristic of the red oak group is that they have bristle-tips; the white oak group does not.

Leaf Base Shape Flattened Obtuse Wedge-shaped

Pith Comparison Walnut Hickories Sometimes leaf differences are subtle so an analysis of the “3 B’s” is necessary . . .Branches, Buds & Bark. Hickories

Conifers – Group A Leaves scale–like = cedars Leaves needle–like Single needles Clusters of 2 Clusters of 2 & 3 Clusters of 3 Clusters of 5 = cedars = spruce, fir, hemlock = Virginia pine, scotch pine = shortleaf pine = loblolly pine = white pine Scotch pine is mostly grown in Christmas tree plantations

Example #1 – Group B Leaves needle or non needle-like? Opposite or alternate arrangement? Simple or compound? Lobed or entire? Serrated or smooth?

Example #2 – Group B Leaves needle or non needle-like? Opposite or alternate arrangement? Simple or compound? Lobed or entire? Serrated or smooth? With or without bristle-tips?

References Harrar and Harrar. Guide to Southern Trees. Dover publications. 1962. Mohlenbrock, Robert H. Forest Trees of Illinois. Southern Illinois University. 1980. U.S. Forest Service. Important Forest Trees of the Eastern United States. 1991.