Recognizing Important Tree Species and Their Products -...

Recognizing Important Tree Speciesand Their Products

HOW MANY tree species are there? When

asked, most people respond by saying

they don’t know or they never really thought

about trees being different. Yet, there is a great

diversity of tree species with different

characteristics that lend themselves to different

uses.

Objective:

� Identify important forest tree species.

Key Terms:

�

Important Tree Species

There are many tree species. Forests in one part of the country have different tree species

than forests in other parts of the country. Recognizing that trees are different and that each

type of tree has unique characteristics is important in forestry.

TREE TAXONOMY

Taxonomy is the classification of plants according to natural relationships. Trees are mem-

bers of the plant kingdom and are placed into divisions, classes, subclasses, orders, families,

E-unit: Recognizing Important Tree Species and Their Products

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angiosperms

dehiscent fruits

dichotomous venation

dioecious

gymnosperms

hardiness

indehiscent fruits

inflorescence

leaf venation

monoecious

palmate venation

parallel venation

pinnate venation

taxonomy

genera, and species. Carl von Linné (Linnaeus), a Swedish botanist, proposed this system of

classifying plants.

There are two divisions: Pinophyta and Magnoliophyta. Coniferous species make up the

Pinophyta, and the trees in this division are called gymnosperms. Gymnosperms are plants

that bear naked seeds without an ovary. Broad-leaved species make up the Magnoliophyta, and

the trees in this division are called angiosperms. Angiosperms are plants having seeds borne

within a pericarp.

HARDINESS

Hardiness is a plant’s ability to withstand cold temperatures. Hardiness is one of many

factors that affect plant survival in a specific area. Large bodies of water, well-drained soil, wind

protection, and adequate moisture increase plant hardiness.


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Zone 1 Zone 7

Zone 5 Zone 11

Zone 3 Zone 9

Zone 2 Zone 8

Zone 6

Zone 4 Zone 10

Below -50°F 0 to10°F

-20 to -10°F Above 40°F

-40 to -30°F 20 to 30°F

-50 to -40°F 10 to 20°F

-10 to 0°F

-30 to -20°F 30 to 40°F

1

7

2

8

3

4

9

5

10

11

11

6

FIGURE 1. A typical hardiness map.

A hardiness map is useful in determining the average low temperatures in a given area. Both

the Arnold Arboretum and the U.S. Department of Agriculture publish hardiness maps. Har-

diness ratings are meant only as guides and should not be looked upon as limiting factors in

plant use.

TREE IDENTIFICATION

To identify woody plants successfully requires a working knowledge of taxonomic termi-

nology and concise mental pictures of leaf, bud, stem, flower, and fruit morphology. The leaf,

twig, bark, and fruit are the most commonly used characteristics for tree identification. Each

kind of tree, whether broad leaved or coniferous, has certain characteristics that make it dis-

tinctive from other species.

Leaf Morphology

Most trees can be identified by

the type, size, shape, color, tex-

ture, and arrangement of leaves.

Angiosperms have broad leaves,

while gymnosperms have needle-

like leaves.

Broad Leaves

A broad leaf consists of one or

more leaf blades and a petiole, or

leaf stem. A bud is located where

the leaf and the stem meet. Broad

leaves may be simple or compound. A simple leaf has a single leaf blade. A compound leaf has

multiple leaf blades, known as leaflets. A palmately compound leaf has each leaflet attached at a

common point. A pinnately compound leaf can have either an odd or even number of leaflets

along an extension of the petiole, called a rachis.

The arrangement of leaves and buds can be used as a basis for identification. Leaves are typi-

cally arranged in an alternate, opposite, subopposite, or whorled fashion. The arrangement in

which leaves are spaced in alternating fashion along the stem is known as alternate. An oppo-

site leaf arrangement is characterized by leaves directly across from each other on the stem.

Subopposite refers to a condition in which the leaves are not spaced sufficiently far apart to be

considered alternate, nor are they perfectly opposite. Whorled refers to a condition in which

three or more leaves are present at a node.

The pattern of veins in a leaf is called leaf venation. If the leaf has a prominent central

vein, or midrib, that extends from the base where the petiole attaches to the blade to the apex

of the leaf, the pattern is known as pinnate venation. If several main veins of approximately

equal size extend from the base of the leaf to the apex of the lobes or the margins of the leaf,

the leaf has palmate venation. In dichotomous venation, the basal veins extend for a


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FIGURE 2. This pine tree is classified as a gymnosperm.

distance and then branch to form a “Y”-type pattern. In parallel venation, the veins run

essentially parallel to each other along the long axis of the leaf.

A tremendous amount of terminology is related to leaf shapes, bases, margins, and apices.

Needle-like Leaves

Needle-like leaves can be of different shapes. Three common shapes are scale-like, awl

shaped, and needle-like. Scale-like foliage overlaps like the shingles on a roof or the scales on a

fish. This type of foliage is relatively soft to the touch. Needles shaped like awls are usually

very sharp to the touch. Needle-like foliage can be born singly or in clusters along the stem.

The needles may be relatively flat (two sided) or angular in cross section.

Twig Morphology

During autumn and winter, tree identification is based on bud, stem, and bark characteris-

tics. Buds and stems are the principal means of identification.

The shape, size, color, and texture of buds offer interesting identification characteristics.

Leaf scars often provide distinguishing features. The shape of leaf scars and the vascular bundle

arrangement are often used to identify plants.

Lenticels, lip-shaped structures composed of corky cells, are produced through the action of

the cork cambium. They are beneficial for identification because of their different colors and

sizes.

Bud scales, by their size, color, shape, or markings, offer good characteristics for identifica-

tion. The terminal bud scale scar is the place where the previous year’s bud scales were

attached. As the buds open and expand in spring, the scales abscise and leave a distinct scar

around the stem. This scar can be useful for gauging the linear growth in a particular season or

over a number of seasons.


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ParallelVenation

PinnateVenation

PalmateVenation

FIGURE 3. Vein patterns in various leaves.

Pith is a very valuable plant tissue for differentiating closely related plants. Pith is derived

from a primary meristem. The color and texture of pith can often be used for separating simi-

lar plant types.

Bark

On deciduous trees, bark is the most important

identification feature in the dormant winter period.

Bark varies in thickness, roughness, type of fissures,

and color. Each year the cambium lays down an

annual ring of new cork cells (bark), forcing the old

bark outward. Since the outer bark cannot stretch, it

fissures or cracks into plates, ridges, and scales, form-

ing the bark characteristic of each species.

Flowers

Flowers are important components of positive tree

identification. The flowering periods of most woody

plants average 7 to 14 days. There are numerous vari-

ations in flower shape, but the reproductive parts—

stamens and pistils—are essentially similar.

A flower that has all the parts (sepals, petals, sta-

mens, and one or more pistils) is called complete.

Incomplete flowers lack one or more whorls of floral

parts. Imperfect flowers lack either stamens or pistils.

Perfect flowers have both stamens and pistils.


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FIGURE 4. Each species of tree has its own pattern

of bark.

Petal

Anther

Filament

Stamen

Sepal

Pedicel

ReceptacleOvary

Pistil

Stigma

Style

FIGURE 5. Diagram of a perfect flower.

Trees may be monecious or dioecious. Monoecious means that staminate and pistillate

flowers are present on the same plant but in different structures. Dioecious means the stami-

nate and pistillate flowers are borne on different plants.

Some trees have solitary flowers, and others have flowers borne on structures called inflo-

rescences. An inflorescence is a collection of individual flowers arranged in some specific

fashion.

Fruit

Fruit offers positive identification features. The longitudinal section of the typical flower

presents a representative view of the ovary. The ovary is the forerunner of the fruit and is

defined as an unripened fruit. The ovary is composed of one or more carpels. A carpel is a

highly modified leaf-like structure that encloses ovules (forerunners of seeds).

A simple fruit consists of a single enlarged ovary composed of one carpel. Simple fruits can

be divided into two major groups: dry and fleshy. Dry fruits can be divided into indehiscent

and dehiscent.

Indehiscent fruits are fruits that do not split open at maturity. There are several types,

including achene, samara, and nut. An achene is a one-seeded fruit with the seed attached at

only one place to the pericarp. The pericarp is very close fitting and does not split open, at least

along regular established lines. A samara is usually one seeded, with a membranous wing that

develops from the pericarp. A nut is a bony, hard, one-seeded fruit. The pericarp is bony

throughout.

Dehiscent fruits split open when mature. There are several types, including legume, fol-

licle, and capsule. A legume (pod) is composed on one carpel and opens along two sutures. A

follicle is composed of one carpel but splits open at maturity along one suture, exposing several

seeds. A capsule is a many-seeded fruit formed from more than one carpel. The carpels are

united.

Several types of fleshy fruits are common with forest trees, including berry, drupe, and

pome. When the entire pericarp is fleshy, the fruit is called a berry. With a drupe, the pericarp

is clearly differentiated into three layers: the exocarp, the mesocarp, and the endocarp. With a

pome, the pericarp is surrounded by the floral tube, which becomes fleshy and tasty.

Two types of compound fruit are aggregate fruit and multiple fruit. An aggregate fruit con-

sists of two or more carpels. It develops from a single flower that contains many pistils. Several

fruitlets are massed on one receptacle. A multiple fruit consists of several flowers that are more

or less united into one mass.

MAJOR FOREST TREE SPECIES

There are many forest tree species with economic importance.

The term southern pine is applied in the lumber trade to shortleaf pine, loblolly pine, slash

pine, and longleaf pine. The term yellow pine, derived from the yellowish color of the wood, is

equally common for these species. Southern pine lumber has a variety of uses. These include

heavy structural and light framing, interior finish, flooring, sheathing, crates, boxes, railcars,


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and many other industrial uses. Southern pine wood readily takes preservative treatment.

When treated, it is used extensively for poles, piling, fence posts, crossties, foundation timbers,

and other construction materials.

Ash is slightly lighter in color than oak, straight grained, and similar in appearance to plain-

sawn oak, with the exception of having no visible medullary rays. Ash wood possesses high-

strength properties. Ash wood is used to make baseball bats, polo and hockey sticks, play-

ground equipment, skis, tennis rackets, handles for shovels and rakes, trim, doors, and other

woodwork. Ash wood has extensive use in bent wood parts, as it responds to steam bending.

American beech is known for its slow growth. The beech wood is hard, dense, and light in

color. It has a diffuse-porous structure and numerous medullary rays. Flooring is the most

important product made from beech. Products of the furniture and brush industries, truck

body parts, toys, woodenware, and novelties are other uses for beech.

Cottonwood is a rapid-growing tree. The

wood of cottonwood is soft textured and light-

weight. It has especially long fiber that makes it

strong and tough in proportion to its weight.

Principal uses of cottonwood include shipping

containers, paper production, furniture, agri-

cultural implements, and veneer.

Baldcypress is a deciduous conifer, and its

wood is soft. Baldcypress does not warp or

check and may be depended on to stay in place.

It holds paint well. Principal uses of

baldcypress include interior and exterior trim,

paneling, sash, doors, and fencing.

Elms are divided into two groups, soft elm

and hard elm. Elm is difficult to split. Soft elm

is an excellent bending wood and is used exten-

sively for boats and bent parts. Furniture and

truck body parts are some other uses.

Sweetgum is the most important southern

hardwood. Many industries use the sapwood of

sweetgum for all their needs. The sapwood of

sweetgum is used in furniture, cabinets, con-

tainers, and general millwork.

Black tupelo grows slowly and has a uniform appearance, indistinct annual rings, and an

interlocking grain. It is a tough wood that is difficult to split.

Hackberry wood is creamy white, ring-porous, and uniform in texture. It has a high resis-

tance to warping and shrinkage. The wood is used extensively in the furniture industry and in

the making of veneer.

No wood compares to hickory for strength, toughness, and elasticity. Hickory is used to

make tool handles, skis, veneer, and rungs on ladders.


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FIGURE 6. Among the uses for wood from cottonwood trees

are shipping containers, furniture, and agricultural

implements.

The wood of pecan hickories has a pleasing grain pattern and is not as hard as the wood of

true hickories. Pecan wood is used to make furniture, flooring, decking in railroad cars, trailer

parts, and expensive cabinets.

The wood of magnolia is soft, fine textured, and straight grained. The wood is excellent for

interior trim, paneling, furniture, veneer, and doors.

Soft maple is used for furniture, paneling, toys, shipping containers, and specialty kitchen

cabinets.

No hardwood is more widely known or used than

oak. Two groups of oak are the white oak group and

red oak group. Oak is a universal wood, used for

many purposes. Oak wood is well adapted to any fin-

ishing treatment. Its strength is ideal for structural

use. It is unequaled for flooring and makes the best

railroad ties. White oak is used for barrels and casts

for liquids. Other uses for oak include decking for

railroad cars, furniture, millwork, and novelties.

The wood of the sycamore is fairly hard, stiff, and

strong. Sycamore is used in furniture and furniture

parts, millwork, and novelties.

Yellow poplar is known for its ability to resist

warping and to take a smooth, lasting paint or enamel

finish. Yellow poplar is used in furniture, as core

stock in veneer, and for wood boxes, exterior trim,

piano parts, fixtures, toys, and novelties.

Black willow is one of the lightest and softest

woods in North America, yet it is a strong wood.

Black willow uses include paneling, furniture, cas-

kets, shipping containers, interior trim, veneer, and

toys.

Honeylocust wood is used in the manufacture of furniture, pallets, and skis.

Sassafras wood is a very durable, hard-textured wood used in manufacturing furniture. It is

also used in boat construction, oars, exterior trim, and general millwork.

Eastern redcedar is most commonly used in the making of cedar chests and in the lining of

closets.

Atlantic white cedar is used for boat planks, tank stock, shingles, millwork, and lumber for

crating.

Red mulberry is used in the manufacture of caskets.

At one time, red bay was in demand for use in shipbuilding.

Black walnut is used in quality furniture, gunstocks, caskets, and specialty items.

American holly is used for making piano keys, cabinets, veneer, and fancy inlays.

Southern catalpa is used to make fence posts.

Black cheery is used in quality furniture, interior trim, paneling, and cabinet making.


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FIGURE 7. Oak trees produce the most common

hardwood.

Persimmon wood is hard and strong and is in demand for golf club heads and weaving

loom shuttle blocks.

Basswood does not significantly warp and is used for molding, Venetian blinds, core stock

for veneer paneling, excelsior, food containers, pulpwood fruit containers, and tongue

depressors.

Douglas-fir is the most important commercial tree species in the United States. The wood

is primarily used for dimensional lumber and plywood veneer.

Red alder wood is lightweight and has low shrinkage. It is used for furniture, doors, sash,

panel stock, and millwork.

Aspen wood is straight grained and easily worked. It is used for lumber, pulpwood, veneer,

excelsior, matches, pallets, boxes, crating, and particleboard.

Paper birch is used for turned products, while yellow and sweet birch are primarily used for

furniture, crates, barrels and casks, interior finish, baskets, and woodenware.

Alaska cedar is used for furniture, small boats, and novelties.

Balsam fir wood is lightweight and is mainly used for pulpwood.

Western fir wood is lightweight but strong. It is primarily used for lumber and general mill-

work.

Eastern hemlock is coarse, lightweight, and low in strength. It is primarily used for lumber

and pulpwood and in the manufacture of boxes and crates.

Western hemlock is a lightweight wood of moderate strength. The wood is principally used

for pulpwood, lumber, plywood, and the manufacture of boxes, crates, flooring, and pallets.

Incense cedar wood is lightweight, is moderately low in strength, and has a spicy odor. The

wood is used principally for lumber and fence posts.

Eastern white pine wood is lightweight and mod-

erately soft. It is mainly used for lumber.

Ponderosa pine wood is used mainly for lumber

and to a lesser extent for poles, posts, veneer, ties, and

piles.

Sugar pine wood is easy to work and is used

almost entirely for lumber products.

Western white pine wood is lightweight and mod-

erately low in strength. It is used for lumber and in

building construction.

Redwood, or sequoia wood, is easy to work and is

resistant to decay. The wood is used for building,

cooling towers, tanks, house siding, shingles, and hot

tubs.

Eastern spruce wood is moderately lightweight

and easily worked. It is primarily used for pulpwood.

Sitka spruce wood is a desirable wood for musical

instruments because of its resonance qualities. The

wood is also used for lumber, pulpwood, cooperage,

furniture, millwork, and boats.


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FIGURE 8. Ponderosa pine trees.

Summary:

� Coniferous tree species are called gymnosperms. Broad-leaved species are calledangiosperms.

Hardiness is a plant’s ability to withstand cold temperatures.

The leaf, bud, stem, flower, and fruit of a tree are useful in identifying the species.Most trees can be identified by the type, size, shape, color, texture, and arrangementof leaves. Angiosperms have broad leaves, while gymnosperms have needle-likeleaves. During autumn and winter, tree identification is based on stem, bud andbark characteristics. Some trees have solitary flowers, and others have flowers borneon structures called inflorescences. Simple fruits can be divided into two majorgroups: dry and fleshy. Dry fruit types include achene, samara, nut, legume, follicle,and capsule. Types of fleshy fruits are berry, drupe, and pome. Two types of com-pound fruit are aggregate fruit and multiple fruit.

There are numerous tree species with economic importance.

Checking Your Knowledge:

� 1. How do gymnosperms and angiosperms differ?

2. What is hardiness?

3. What are the different types of leaf structures and shapes?

4. What features of a leaf, bud, stem, flower, and fruit are used in plant identifi-cation?

5. What are some economically important tree species?

Expanding Your Knowledge:

� Identify tree species in your area using a key or knowledge of leaf, bud, stem,flower, and fruit morphology.

Web Links:

� 680 Tree Fact Sheets

http://hort.ufl.edu/trees/

United States Forest Service Tree List

http://www.fs.fed.us/database/feis/plants/tree/

Arborday.org Tree Guide

http://www.arborday.org/treeguide/


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http://hort.ufl.edu/trees/

http://www.fs.fed.us/database/feis/plants/tree/

http://www.arborday.org/treeguide/

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