Name Osage Orange
Location North America
Texture/Grain Fine/Open
Specific Gravity 0.7
7
Hardness
Very Hard
Strength
Strong
T/R Stability
N/A

 

Guide

Woodworking
Know-How

Wood &
Woodworking
Materials

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Hardwoods
& Softwoods

1. Wood Botany
(You are here.)

2. Mechanical
Properties

3. Physical
Properties

4. Health Hazards

5. Comparing &
Choosing Woods

6. Hardwoods &
Softwoods Resources

        

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hen selecting a wood species for a project, it helps to know some of the botanical traits that set hardwoods and softwoods apart from each other. It’s commonly believed that hardwoods come from deciduous trees and softwoods come from conifers. Basically, this is true, but there’s more to it than that.

 

Angiosperms
Hardwoods come from angiosperms, which means the plant seeds are encased in a “seed vessel” like a fruit or a nut. There are two types of angiosperms: monocots (such as palm and bamboo) and dicots (such as oak and rosewood). Almost all hardwoods come from dicots. Most dicots in temperate climates are deciduous, meaning they lose their leaves during winter dormacy. Dicots in warmer parts of the world don’t lose their leaves — at least, not all at once. So, contrary to the standard definition, not all hardwoods come from deciduous trees.

Gymnosperms
Softwoods come from gymnosperms, plants with naked seeds. As the seeds develop on the cones, they are not encased in any tissue. Within this botanical group, there is a subdivision of conifers, which are characterized by needle and scale-like foliage. All softwoods come from coniferous gymnosperms.


The distinguishing factor between hardwoods and softwoods is how the trees reproduce. Hardwoods grow from encased seeds (oak, top), softwoods from seeds arranged on cones (pine, bottom).
Microscopic Attributes
Botanical categories, while interesting, make little difference to most craftsmen. To find the traits that affect your woodworking, you must look closer.

Hardwood Cell Structure
Study a piece of hardwood under a microscope and you’ll find five major types of cells. Four of these are longitudinal cells, running parallel to the length of the trunk or limb.

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Most hardwood tissue is composed of fibers 100 times longer than they are wide. These have thick cell walls, sometimes appearing almost solid.

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Interspersed among the fibers are vessel elements. These appear much larger in diameter and shorter than fibers, and they are always aligned to form long, longitudinal pipelines. When sliced open, they appear as pores in the wood surface.

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You may also find a small number of tracheids and parenchyma cells with much thinner cell walls than fibers. These are few and far between and are completely missing in some hardwood species.

The fifth cell type runs perpendicular to the others:

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Ray cells form radial pipelines running out from the center of the tree.

Hardwood Grain
The appearance of a hardwood’s grain depends on the size, shape, and number of each cell type. And because there are so many possible combinations, hardwood grain is enormously varied. For example, the rays can grow quite large, producing a pronounced ray fleck in some species. In quartersawn oak, for example, the rays are the first thing you see. In other woods, they are barely noticeable.

Grain differs with the distribution of cells in the growth rings. When the cells in the summerwood are roughly the same size and density as the springwood, the wood has an even grain texture. When the summerwood cells are noticeably smaller and denser than those in the springwood, the texture is uneven.

Vessel elements and the pores they create also have a conspicuous effect. Hardwoods with large pores are said to have an open grain. Those with extremely small pores (too small to be seen with the naked eye) have a closed grain.

Softwood Cell Structure
Softwoods have a much simpler structure. Between 90 and 95 percent of the wood is composed of tracheids, while the rest are ray cells. There may also be a small number of parenchyma cells. There are no fibers or vessel elements, although some softwoods have resin canals lined with epithelial cells.

Softwood Grain
Because there are no fibers in softwoods, they tend not to be as dense or as hard as most hardwoods. And because there are fewer types of cells, there is less variety in the grain and appearance. For example, the absence of vessel elements eliminates the pores on softwoods. The grain is neither open nor closed — these terms don’t apply to softwoods.
 


The cells that make up hardwood.*


The quarter grain surfaces of lumber where the wood species has large ray cells shows pronounced ray fleck.*


The long grain surfaces of Red Oak display an uneven grain pattern, while those of Honduran Mahogany are much more even.*


The cells that make up softwood.*

Chemical Attributes
Although most wood tissue is composed of strands of cellulose fibers stuck together with lignin, there are many other chemicals and minerals embedded in this matrix. 

Wood Extractives
Extractives, as the embedded substances are known, differ from species to species. A particular mix is what gives wood its characteristic color. But color is just one of the effects of extractives.

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Extractives can effect the density and strength of the wood species. The more extractives that are embedded in the fibers, the denser and stronger the wood.

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Many extractives are minerals. These act as fine abrasives, dulling your cutting tools as you work.

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Some are resinous and waxy substances. These build up as pitch on the cutting surfaces of power tools and interfere with the cutting action. They can also make a wood difficult to glue or finish.

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Many are antibiotics, killing molds and bacteria that would cause disease and rot. Woods high in these chemicals are resistant to decay.

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A few of these antibiotic chemicals are toxic to humans as well as microbes and have been known to cause or aggravate allergic reactions, respiratory ailments, and other health problems

These botanical, microscopic, and chemical attributes all combine in a wood species to give it distinct characteristics or properties. These can be divided into two general categories, mechanical properties and physical properties.
 

 
Tastes like the inside of an old barrel – Fine wine, particularly red wine, is often aged in oak barrels to enhance its taste and aroma. Many of the extractives in oak are soluble in alcohol. These dissolve into the wine as it ages, modifying its flavor and smell. The chemical vanillin, for example, gives the wine a vanilla taste. Eugenol tastes like clove spice; guaiacol has a smoky aroma; and there are dozens more. A savvy cooper can work with a vintner to create a unique taste simply by how they make and prepare the barrels. Green oak, for example, has a much higher concentration of eugenol than seasoned wood. Toasting or charring the inside of a barrel increases vanillin and guaiacol.
"Toasing" a wine barrel.

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*Indicates that you can enlarge a photo by clicking on it. To reveal the information in a "Superphoto," first enlarge it and then move the cursor over it.

 "Abundant to all the needs of man, how poor the world would be without wood."
Eric Sloane in Reverence for Wood

 

Wood and Woodworking Materials/Hardwoods and Softwoods/Wood Botany
part of the Workshop Companion,
essential information about wood, woodwork, and woodworking
necessary to woodworkers and practitioners of the wood arts
to become competent craftsmen.
By Nick Engler.

Copyright © 2009 Bookworks, Inc.