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<FONT SIZE=4><P ALIGN="CENTER">IDENTIFICATION OF CONIFER TREES</P>
</FONT><P>PURPOSE: To identify some conifer trees using a dichotomous key.</P>
<P>MATERIALS: Twig samples with masking tape labels, hand lenses, metric ruler, Key to Conifer Trees.</P>
<P>INTRODUCTION: Conifer trees produce their seeds in cones. Most of them are evergreen trees since they keep their leaves (usually called needles) all year long. Deciduous trees, such as beech and maple, shed their leaves in the fall. A few conifers also shed their leaves in fall. </P>
<P>Evergreen conifer trees are easy to spot in the winter, and they can be readily identified by their leaf and twig characteristics. Which conifer trees grow in your area? To answer this question you will use a dichotomous key. </P>
<P>HOW TO USE A DICHOTOMOUS KEY: The word <U>dichotomous</U> means "separating into two groups", which describes the kind of choices that must be made in using such a key. Starting at the top of the key you must choose between 1A and 1B. The choices are opposites. The tree you are trying to identify MUST fit into one group or the other. After you have made your decision, you are given the name of the tree, or directed to go to the number of the next choice. You continue to make decisions until you arrive at an identification.</P>
<P>PROCEDURE:</P>
<P>A. You will be given twigs, identified by letter, that were taken from different species of conifer trees. Each sample has its picture on your data sheet.</P>
<P>B. Use the dichotomous key to identify the tree from which each twig was taken. Record the choices you made (1A or 1B, 2A or 2B, and so on) and the description (characteristics) of the tree on your data sheet. Then record the name of the species.</P>
<P>C. After you have correctly identified all of the tree species, test your ability to identify conifer trees outside. Find several kinds of evergreen trees growing near school or home, and use the dichotomous key to identify them. Soon you will be able to identify evergreen trees without using the key!</P>
<P>QUESTIONS:</P>
<P>1. What is the purpose of a dichotomous key?</P>
<P>2. What characteristics do all conifers share?</P>
<P>3. What characteristic used in the key will help you distinguish between a pine and other conifers?</P>
<P>4. What characteristics will help you to identify the different species of pine?</P>
<P>5. What are the most common native conifer trees found in your area?</P>
<P>6. What are the most common conifer trees people have planted in their yards?</P>
<P>7. What kinds of conifers are used for Christmas trees? Why would tamarack (larch) make a poor Christmas tree?</P>
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KEY TO CONIFER TREES
Northeastern Gymnosperms
1A. Tree deciduous; spur shoots (enlarged bumps) mark needle sites on
winter twigs.....Larix laricina (Tamarack)
1B. Tree evergreen; leaves present as needles or scales on winter twigs......2
2A. Leaves scalelike, overlapping............................................3
2B. Leaves needlelike, not overlapping.......................................5
3A. Twigs flattened, fan-like................................................4
3B. Twigs rounded or 4-angled.........Juniperus virginiana (Eastern Red Cedar)
4A. Leafy twigs 2-3 mm wide..........Thuja occidentalis (Northern White Cedar)
4B. Leafy twigs about 1 mm wide..Chamaecyparis thyoides (Atlantic White Cedar)
5A. Needles in clusters......................................................6
5B. Needles occurring singly................................................11
6A. 2 needles/cluster........................................................8
6B. More than 2 needles/cluster..............................................7
7A. 3 needles/cluster................................Pinus rigida (Pitch Pine)
7B. 5 needles/cluster.......................Pinus strobus (Eastern White Pine)
8A. Needles more than 12 cm long.....................Pinus resinosa (Red Pine)
8B. Needles less than 12 cm long.............................................9
9A. Needles flat, dark green.......................Pinus banksiana (Jack Pine)
9B. Needles angular, blue-green or gray-green...............................10
10A. Needles blue-green, twisted.................Pinus sylvestris (Scotch Pine)
10B. Needles gray-green, twisted...............Pinus virginiana (Virginia Pine)
11A. Needles 2-ranked (one row of needles on each side of twig)..............12
11B. Needles extending from all sides of twig................................13
12A. Needles stalked, on woody cushions..............Tsuga canadensis (Hemlock)
12B. Needles stalkless, leaving round, depressed scars.........Abies balsamea
(Balsam Fir)
13A. Needles soft, flattened....................Taxus canadensis (American Yew)
13B. Needles stiff, 4-angled.................................................14
14A. Twigs smooth, not hairy; needles blue-green, produce a bad odor when
crushed..........Picea glauca (White Spruce)
14B. Twigs hairy.............................................................15
15A. Needles dark green, shiny........................Picea rubens (Red Spruce)
15B. Needles pale blue-green in color..............Picea mariana (Black Spruce)
KEY TO SELECTED CONIFER TREES
Western Gymnosperms
1A. Tree deciduous; spur shoots (enlarged bumps)present where needles were
once present...............Larix ccidentalis (Western Larix)
1B. Tree evergreen; leaves present as needles or scales on winter twigs.....2
2A. Leaves scalelike and overlapping, or both scalelike and needle like.....3
2B. Leaves needlelike only, not overlapping.................................7
3A. Leaves single..............................Sequoia sempervirens (Redwood)
3B. Leaves in pairs, threes, or fours; scalelike............................4
4A. Twigs flattened, fan-like...............................................5
4B. Twigs rounded or 4-angled........Juniperus occidentalis (Western Juniper)
5A. Leafy twigs distinctly longer than broad..........Libocedrus decurrens
(Incense-cedar)
5B. Leafy twigs about as long as broad......................................6
6A. Leafy twigs 2-3 mm wide..................Thuja plicata (Western Redcedar)
6B. Leafy twigs about 1 mm wide.....Chamaecyparis nootkatensis (Alaska-cedar)
7A. Needles in clusters......................Pinus ponderosa (Ponderosa Pine)
7B. Needles occurring .singly...............................................8
8A. Needles 2-ranked (one row of needles on each side of twig)..............9
8B. Needles extending from all sides of twig...............................11
9A. Needles stalked, on woody cushions.....................................10
9B. Needles stalkless, leaving round, depressed scars.....Abies lasiocarpa
(Alpine Fir)
10A. Needles flattened, sharp pointed...........Taxus brevifolia (Pacific Yew)
10B. Needles 4-angled, blunt pointed......Tsuga heterophylla (Western Hemlock)
11A. Needles flattened.....................Pseudotsuga taxifolia (Douglas-fir)
11B. Needles 4-angled......................Picea engelmanni (Engelmann Spruce)
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