CTFO Education Site



TEACHING PLANS Lesson Five: Identifying Christmas Trees

During the seasonal celebration, we all have a favourite type of Ontario evergreen tree. What species is it? We often call pine, spruce and fir trees "Christmas trees" but the proper name for them is coniferous trees. We also call them evergreens because they are the only plants that can hold their needles all winter.

Desired Learning Outcome:


1.) To have children able to distinguish between pines, spruces and firs they may see in their homes and in the homes of friends, by recognizing key characteristics such as shape, arrangement of needles and colouring. To recognize these same characteristics in trees growing outside.

Background:


- There are over 600 different kinds of conifers and four common Christmas tree varieties.
-"Conifer" means cone-bearer.
- Leaves of all trees and plants perform photosynthesis.
- Coniferous tree needles have special adaptations which allow them to survive harsh climates.

Teaching Suggestions:


1.) Distribute copies of the student information package, Identifying Christmas Trees. If possible, provide the children with samples of spruce, pine and fir trees which should be readily available at local tree lots in late November and into December. Growers will also often provide cross-sections of tree trunks to enhance your classroom presentations.

2.) Have the children compare the leaves of any broadleaf plant with the needles of a conifer. Ask them to look carefully for the stomata under each leaf - with magnifying glass if possible - and to describe the comparative texture of the broadleaf and the needleleaf - the needleleaf has a waxy coating, few stomata and is stiff because it is soaked in resin which resists freezing.

3.) Remind the children that deciduous trees drop their leaves in the winter while coniferous trees (with some exceptions) drop their needles continuously but never all at once.

4.) Remind the children that conifer literally means cone-bearer and that cones produce seeds on conifers just as flowers produce seeds on most plants and trees. Cones are an important aid to identify coniferous trees but may not be totally reliable since many conifers produce cones at irregular intervals.

5.) Point out the essential differences among the three principle coniferous species. Pines produce long, slender needles in clumps of two to five; spruce needles are short and square; firs grow needles that are flat, short and arranged in two rows on either side of the twig. Spruce needles will easily roll between the children's fingers; fir needles which are flat, will not. The colour of the twig and the texture of the bark are also important clues to identification.

Suggested Questions:


1.) Look at the sample branches you have. Describe the needles. Are they short; long; stiff; soft ? Explain how they are arranged on the twig. Do they grow in clumps or grow singly from the twig ? How do the needles smell when you crush them?

2.) Tell us about the twigs. Describe the colour. Are they whitish-grey or yellowed like spruce; greenish or orangey-brown like white pine; or greenish and waxy like the balsam fir ?

3.) Describe the cones. Do they seem to stand up straight on the branch like the fir or do they hang from the branch like the pine and white spruce? Describe the shape of the cones. Are they long and narrow or short and blunt? Are they open or closed?

Suggested Class Activity: Overhead projection: Unscramble the Mixed-up Trees,


STUDENTS' PACKAGE Lesson Five: Identifying Christmas Trees

The coniferous trees we decorate during the festive season are members of an amazing family of plants. Some conifers, like the giant Douglas firs that grow in British Columbia, are among the largest trees in the world, while others, like the tiny shrubs that grow on many front lawns, are among the most attractive.

We often refer to conifers as Christmas trees but in fact, besides the spruce, pine and fir trees which we decorate in December, there are over 600 different kinds of conifers. The name conifer means "cone bearer"; every conifer produces its seeds in cones. Another name for conifers is evergreen because most conifers hold their needles through-out the winter. Trees that shed their needles in the fall and remain dormant throughout the winter are called deciduous or broadleafed trees.

The leaves of all trees and all plants serve a special purpose. Through a process called "photosynthesis", they transform minerals and water from the soil and carbon dioxide from the air to make a food called carbohydrates. The energy that drives this process comes from sunlight. In many ways the needles of deciduous trees are better food producers because, being broader, they can absorb more sunlight.

The leaves on coniferous trees are much smaller and are called needles. They are amazingly adapted. The needles on conifers have fewer stomata than are found on deciduous needles. The needles are also coated with wax which prevents the loss of water and are soaked in resin which helps the needle withstand freezing. Even the shape of the needles is an asset in winter because it offers no resistance to the wind.

As a result of all these adaptations, conifers can grow where broadleaf trees cannot, in the far north where the soils are shallow and poor and the moisture is locked in the ice most of the year; on the edges of deserts where the winds are strong and the soil is sandy and dry; and high in the mountains. Another advantage of coniferous trees is that because they can hold their needles all winter they can begin the process of photosynthesis early in the spring as soon as the sun gets warm and the ice melts.

The characteristics of coniferous and deciduous trees determines where each will grow. Deciduous trees grow in the tropics and in temperate regions while conifers span the north polar cap of the world and are common in the north of Europe, Asia and Canada. Both deciduous and coniferous trees are common in the Great Lakes - St. Lawrence forest that spans Southern Ontario.

Once every year coniferous trees become especially important to us all. However, many people decorate their trees without knowing what type of tree it is. The best way to identify any tree is to look closely at its leaves or needles. This is true of conifers as well. Even though at first glance all needles might seem to be the same, they are actually quite different. After looking at the needles, other clues can be found in the shape of the cones, if there are any, and the colour and texture of the bark.

In Ontario the four most common Christmas tree species are Scots pine, White pine, Balsam fir and White spruce. With practice you can easily tell them apart. Study the descriptions and illustrations carefully and remember to look closely at your own tree.

SCOTS PINE - Pinus sylvestris

The Scots pine, which is the most popular Canadian Christmas tree, is not a native of North America. In spite of its name the Scots pine is found throughout Europe and Asia. Introduced to Canada by Christmas tree farmers, it can now sometimes be found growing in the wild. The Scots pine is a thick, hardy tree that holds its needles well over the holidays. Trees grown on a farm respond well to pruning and grow in well-rounded conical shapes with few breaks in the foliage.

Characteristics:
The colour of a Scots pine is variable; some trees may be blue-green while others are yellow-green. The needles appear in clusters of two, are usually twisted and are about four to eight centimeters long. The bark on the upper portion of the stems is orange or orangeish-brown and is smooth to the touch. Closer to the trunk it is a greyish or reddish-brown and the trunk is often fissured in scaly plates. The cones grow both singly and in groups of two to three and are up to eight centimeters long. They are usually yellow-brown and contain tiny prickles on the cone scales.

WHITE PINE - Pinus strobus

Many people think that the graceful White pine is the most beautiful of all Christmas tree varieties, even though its soft needles make it difficult to decorate. The White pine is the largest tree that grows in Eastern Canada and can be seen in the north, towering above the boreal forest. In the wild it can reach diameters of 1.5 metres and heights of 45 metres. Because of its size and strength the White pine was once used to make the masts of sailing ships. Today it is valued by carpenters because its smooth, white wood contains few knotholes and it doesn't twist or shrink.

Characteristics:
The needles are five to twelve centimeters long, are soft and flexible and appear in bunches of five. The bark is smooth to the touch and is greyish-green near the tips of the branch, becoming rougher and a darker grey-brown closer to the trunk. The cones mature in the fall and drop from the tree during the winter. Usually eight to twenty centimeters long, and three centimeters in diameter, the cones contain 50 to 80 scales arranged in five spiral rows.

BALSAM FIR - Abies balsamea

The range of the Balsam fir is almost entirely in Canada and stretches from Newfoundland to Alberta. In the wild, firs take the shape of tall, narrow pyramids about 23 metres high. The wood of the tree is valued by the pulp and paper industry, while its thick, oily sap is used to make some medicines. Fir trees hold their needles well and are a good choice if the decorated tree is to be left standing for a long period of time.

Characteristics:
Balsam bark is smooth on young trees and dotted with blisters filled with resin. The small, blunt cones are oblong, about six centimeters long and two and a half centimeters wide and appear in bunches. They stand upright on the branch. The needles are two to three centimeters in length, are rounded at the tip and are a dark, shiny green in colour. Unlike spruce needles, fir needles are flat and will not roll between your fingers.

WHITE SPRUCE - Picea glauca

This is the most valuable of the many varieties of spruce which dominate the Boreal forest and is much sought after by pulp and paper companies. It grows in every province and territory in Canada achieving a normal height of about 24 metres and a diameter of about 60 cm. The strong slender twigs which hold ornaments well, the dense foliage and symmetrical proportions of the spruce make it a very beautiful Christmas tree. The spruce needs lots of water however, and must be watered regularly to prevent it from losing its needles.

Characteristics:
The bark on a young tree is grey to reddish-brown, becoming scaly as the tree ages. The cones appear in attractive clumps and are very much like ornaments themselves. The needles are about two centimeters long, and are an attractive dark green or bluish green. The needles of spruce and fir trees are quite similar, but on spruce, the needles are square to round in profile and will roll between your fingers. They are stiff and slightly curved and give off a sharp pungent odour when crushed.


conifer - means cone bearer; conifers produce their seedsin cones. Most conifers are evergreen because they hold their needles throughout the winter
coniferous - a cone bearing tree such as spruce or pine. The foilage is usually evergreen
deciduous - plants which shed their needles annually. Deciduous trees include the broadleaf Maples, Oaks, Poplars and Elms

photosynthesis
- the process by which green plants manufacture sugar from water and carbon dioxide from the air. Oxygen is released into the air through this process. Green plants, through photosynthesis, help purify our air
 
stomata - pores that appear on the underside of needles and allow the escape of moisture between the tree and the air. Coniferous needles have very few stomata, which helps to conserve moisture

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Christmas Tree Farmers of Ontario.

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