Tree Identification

1103

Jennifer Woods

PowerPoint 1 - Leaves

Tree Identification Characteristics In order to correctly identify trees in nature it is

important to know certain characteristics used in tree identification.

Looking at characteristics other than leaves of a tree will help to identify it. This helps when there are no leaves on a tree or they are too high to see properly.

These are just some of the techniques used in tree identification.

Tree Identification Characteristics Some of these characteristics that should be looked

at when identifying a tree are: Leaf shape Twigs and buds Bud scars Fruit Flowers Bark Tree form/Branching pattern Where the tree is growing and what other plants and

trees it may be growing around.

Leaves Leaves are the best and often the easiest way to

identify a tree. Needles and scale of evergreens are also considered

leaves. Questions to consider when identifying leaves:

Are the leaves: simple or compound?  margins smooth or margins rough?  any sinuses or lobes? What is the size, shape, texture, and color variation of the

leaves?

Leaves – Simple or Compound Simple leaves only have one leaf blade. Compound leaves are made up of several

separate leaflets attached to a common leaf stem.

Leaves - Margins Margins are the edges of the leaves, which have

different patterns. Examples of margins are:

Smooth Serrate or Doubly serrate Dentate Crenate Undulate Sinuate Lobed

Leaves – Sinuses or Lobes A sinus is the indentation between two

lobes. A lobe is a division of a leaf blade that is

broadly attached.

Leaves - Shapes Leaves can come in many shapes. Some examples of leaf shapes are

triangular, oval, or elliptical.

Leaf Arrangements Leaf arrangement refers to the leaf arrangement

on the stem of the tree. Leaves are arranged in three different ways:

Opposite – Buds form in pairs on either side of the twig.

Alternate – Buds are arranged singly at intervals along the twigs.

Whorled – Buds are arranged in circles around the twig.

Leaf Arrangements Most trees have alternate branching.

Tree Identification

1103

Jennifer Woods

PowerPoint 2 – Twigs, Buds, Fruit, Bark, Tree Forms

Twigs and Buds A twig is the current year’s growth on a tree. A bud is where the leaves will eventually grow

from and is located on a twig. Buds can be pointy, blunt, shiny, dull, smooth, hairy, and come in many colors.

A bud scar is where last year’s leaves fell off. Bud scars are unique for every species.

Twigs and Buds Terminal buds are on the end of a twig. The marks inside a leaf scar are called

bundle scars.

Fruit and Flowers Fruit is the matured ovary of a flowering plant – the seed

bearing product of the plant. In conifers the fruit is called a cone.

Select fruit types: Drupe Berry Acorn Samara Pome Legume

It is easier to identify a tree by its fruit because it is on the tree longer than flowers.

Fruit and Flowers Many trees do not have perfect flowers, most have

imperfect flowers. Flower and fruit clusters are termed inflorescences. Types of inflorescences:

Spike Raceme Panicle Corymb Umbel Cyme

Bark Bark is a helpful for identification in the fall and

winter when leaves are not available. Bark is the outer layer of the tree that covers the

inner layers of the tree that move nutrients upward to the foliage.

Main bark characteristics are thickness, degree of roughness (smooth, scaly, furrowed), color of outer and inner bark, depth and breadth of fissures, width of fissures, and length of plates.

Tree Forms A tree form is basically the silhouette that a tree

makes. It is the general overall shape of a tree. Trees of the same species will not all have the

same silhouette. Tree forms differ by the tree specie, age of tree,

whether it is in an open or forested area. When using tree forms for identification do not

use trees in a forested area because they may not have had optimal growth due to light and water requirements.

Tree Forms Some examples of tree forms are:

Conical (Balsam Fir) Pyramidal (White Spruce) Slender (Black Spruce) Vase-shaped (American Elm) Oblong (Shagbark Hickory) Drooping (Weeping Willow)

Tree Identification

1103

Jennifer Woods

PowerPoint 3 – Taxonomic Keys, Evergreen Identification, Scientific Names, and Michigan Trees

Taxonomic Key Use When identifying trees it is also helpful to be able to

use tree identification guides and taxonomic keys. The key works by distinguishing differences among

a group of trees by various physical characteristics until only one specie is left.

A taxonomic key is used to identify trees and shrubs by using leaf shape, twigs and buds, seeds, fruit, and cones to narrow a sample down to a specific specie of tree.

Taxonomic keys usually start with a leaf sample.

Angiosperms vs. Gymnosperms Angiosperm – A flowering plant. Gymnosperm – young seeds naked at the time of

pollination, the mature seeds never borne in an ovary or fruit.

Angiosperms are also considered flowering plants. These trees lose their leaves in the winter with the exception of evergreen angiosperms.

The major group of gymnosperms in Michigan are conifers and the major group of angiosperms are the broad leafed trees.

Evergreen Identification Evergreens or conifers are identified differently

than deciduous trees. In evergreens needles or scales do not fall off in

the winter except in a few species like the tamarack.

Conifers have either needles like a white pine or scales like a cedar.

Cone shape, size, and color can also be used in evergreen identification.

Evergreen Identification Needles occur in three ways on evergreens:

Needles grow in clusters of two or more (ex. true pines).

Needles grow in clusters of 10 or more in short lateral shoots (ex. Tamarack).

Needles grow solitary along the branch (ex. spruce).

When identifying evergreens count the number of needles that occur in a group and then length of the needles.

Needles that occur singularly may either be flat or round and have different numbers of white lines on the bottom of the needles.

Needles that are flat may be all scale like as in cedar trees or junipers.

Evergreen Identification

Scientific and Common Names Scientific names are used for standardization so

everyone will know what tree is being discussed since common names change from one area to another.

Scientific names are either italicized when typed or underlined when hand written.

The genus of a scientific name is always capitalized and the species is always lowercase.

Michigan Trees The following are some examples of

common Michigan trees. Included are the common and scientific names of these trees.

Michigan Trees Examples Largetooth Aspen –

Populus grandidentata Basswood – Tilia

americana Beech – Fagus grandifolia White Birch – Betula

papyrifera White Cedar – Thuja

occidentalis Black Cherry – Prunus

serotina

Box Elder – Acer negundo American Chestnut –

Castanea dentata Flowering Dogwood o

Cornus florida American Elm – Ulmus

americana Balsam Fir – Abies

balsamea Hemlock – Tsuga

canadensis

Michigan Trees Examples Shagbark Hickory –

Carya ovata Ironwood – Ostrya

virginia Black Locust – Robinia

pseudoacacia Black Maple - Acer

nigrum Norway Maple – Acer

platanoides Red Maple – Acer rubrum

Silver Maple – Acer saccharinum

Sugar Maple – Acer saccharum

Mountain Ash – Sorbus spp.

Red Oak – Quercus rubra White Oak – Quercus alba Jack Pine – Pinus

banksiana

Michigan Trees Examples Red or Norway Pine –

Pinus resinosa Scotch Pine – Pinus

sylbestris White Pine – Pinus

strobus Austrian Pine – Pinus

nigra Sassafras – Sassafras

albidum Black Spruce - Picea

mariana

Norway Spruce – Picea abies

White Spruce – Picea glauca

Sycamore – Platanus occidentalis

Tamarack – Larix Laricina Black Walnut – Juglans

nigra Black Willow – Salix nigra Witch-Hazel – Hamamelis

virginiana

References Barns, Burton V., Wagner, Warren H. Jr., Michigan Trees The

University of Michigan Press, Ann Arbor. 1985. Burnie, David., Tree Alfred A. Knopf, New York. 1988. Petrides, George A., A Field Guide to Trees and Shrubs

Houghton Mifflin Boston, 1972. Smith, Norman F., Trees of Michigan and the Upper Great

Lakes Thunder Bay Press, Lansing. 1995. Pictures taken from:

http://www.usoe.k12.ut.us/curr/science/sciber00/7th/classify/sciber/taxokey.htm 

http://www.dsisd.k12.mi.us/mff/TreeBasics/TreeIDkeys.htm