Trees are the oldest, Bristlecone Pine (Pinus aristata) and largest,Giant Sequoia (Sequoiadendron giganteum) species on earth. They provide oxygen, remove carbon dioxide from the atmosphere, stabilize the soil, provide food, shelter and numerous products.

Definitions 

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Dendrology

Dendrology stems from the Greek word for tree, 'Dendron', and 'ology' meaning the study of. The study of dendrology includes: identification, silvical characteristics, ranges, taxonomy, morphology and ecology.

A plant is considered to be a tree if it has the following characteristics:usually has a single dominant woody stem (trunk or bole), is capable of diameter growth as a result of the vascular cambium,is a perennial plant,will reach heights over 4.5 metres.

In comparison a plant is considered a shrub if: it is multi-stemmed, is capable of diameter growth as a result of the vascular cambium,is a perennial plant, height is usually less than 4.5 metres.

Classification of Trees and Shrubs

All trees and shrubs are separated in to two Divisions, based primarily on the flower types and seed produced.

Pinophyta - (also found as Gymnosperms in older texts) are the conifers. There are over 700 species world wide and include members of the Pine, Cedar, Yew, and Ginkgo families.

Characteristics of Pinophyta

• leaves are often needle or scale-like,
• seeds are naked, often borne in a cone,
• the wood is composed primarily of tracheids,
• are also commonly known as evergreens however, Larches, Ginkgo, Bald-cypress and Dawn Red-wood lose their foliage each year.

Magnoliophyta - (also found as Angiosperms in older texts) are the broad-leaf trees and shrubs. There are over 200,000 species described in 385 families. Members of Magnoliophyta are divided into two classes. Liliopsida (monocots) include; Palms, Yuccas and Bamboos. The second class Magnoliopsida (dicots) such as: Maples, Oaks, Ashes. All have woody stems.

Characteristics of Magnoliophyta

• leaves are simple or compound,
• fruit requires double-fertilzation,
• woody dicots have both trachea and tracheids in their wood.

Comparing Monocots and Dicots

When learning to identify any objects one of the first problems that may be encountered is the terminolgy. Please click on dendrology definitions for assistance.

The following images should help with separating a number of components that can be used when trying to identify an unknown specimen. These are not intended to be complete descriptions. Texts referenced at the end of the lecture will provide additional material.

Several Leaf Types of Pinophyta

	Needle of Pines are found in groups or clusters.		Needles of Spruce, Balsam Fir and Eastern Hemlock are borne individually on the twig.

	Foliage of Eastern White Cedar consists of over-lapping scales.		The broad-leaf of Gingko.

Several Leaf Types of Magnoliophyta

Simple Leaf

	A simple leaf of White Birch showing the: apex,  margin,  base,  petiole,  mid-rib,  lateral vein.

Pinnately Compound Leaf

	A pinnately compound leaf of White Ash showing the: terminal leaflet,  rachis,  petiolule,  petiole.

	Bi-pinnately Compound Leaf of Honey-locust.		Palmately Compound Leaf of Horse-chestnut.

Leaf Shapes

	Elliptical - the leaf is widest about the middle,tapers to both the apex and base.		Obovate - the leaf is widest above the mid-point.

Apices

	Accuminate - tapers to a long slender point.		Acute - tapers to a broad, wedge shape.

Margins

	Singly serrate - single teeth on the margin.		Entire - there are no teeth on the margin.

Bases

	Truncate - the base is flattened.		Oblique - the margin does not meet evenly.

Winter identification can be a challenge, and rather intimidating. It is helpful to become familiar wtih the terminology, each species does exhibit their own characteristics.

Terminal Bud

	A twig of Butternut showing: Terminal bud,  Leaf Bud,  Flower Bud,  Leaf scar,  Lenticels.

Lateral Bud

	A twig of Butternut showing: Lateral bud,  Leaf scar,  Vascular bundle scars.

When separating species in winter condition start by checking the arrangement of the lateral buds.

	Opposite Arrangement - the lateral buds are directly across from each other. Examples - Ashes and Maples.		Alternate Arrangement - lateral buds are alternately arrranged on the twig.

	Whorled Arrangement - the terminal buds are grouped or clustered. Example - Oaks.

The University of Guelph is currently working on the Ontario Tree Atlas Project. If you are interested in becoming involved as a volunteer contact Rob Guthrie at the University of Guelph. Please click on tree identification to link to other dendrology sites. If you have any comments, suggestions, or find other sites of interest please contact me at, dhendry@flemingc.on.ca.

Dirr, M.A. 1990. Manual of Woody Landscape Plants: Their Identification Ornamental Characteristics, Culture, Propagation and Uses. Champaign,Ill. Stipes, 1007pp.

Elias, T.S. 1980. The Complete Trees of North America: Field Guide and Natural History Toronto: Van Nostrand Reinhold, 948pp.

Farrar,J.L. 1995. Trees in Canada.Markham, Ont. Fitzhenry and Whiteside,502pp.

Harlow, W.M. and Harrar E.S. 1990. Textbook of Dendrology: Covering the Important Forest Trees of the United States and Canada. Toronto: McGraw-Hill,501pp.

Hosie R.C. 1979. Native Trees of Canada. Toronto: Fitzhenry & Whiteside. 380pp.

Little, E.L. 1980. The Audubon Society Field Guide to North American Trees: Eastern Region. Toronto: Random House, 714pp.

Petrides. G.A. 1986. The Peterson Field Guide to Trees and Shrubs: Northeastern and North-Central United States and Southeastern and South-Central Canada. New York: Houghton Mifflin, 428pp.

Sutton, A. and Sutton M. 1992. The Audubon Society Nature Guides: Eastern Forests. Toronto: Random House, 638pp.

Soper, J.H. and Heimburger M.L. 1982. Shrubs of Ontario. The Royal Ontario Museum. Toronto, 495pp.

Return to the Natural Resource Skills Course Outline   or  to go to the tree identification descriptions that students are learning in first semester.