Lesson 5.02: Comparing Hardwood and Softwood Species

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How do hardwoods and softwoods differ according to wood characteristics? 

Trees are divided into two classes: hardwoods, which have broad leaves, and softwoods, which have needle-like leaves or scale leaves and are called conifers.

1. No degree of hardness divides the hardwoods from the softwoods. Some hardwoods are soft and some softwoods are hard.
   • The term softwood originated in New England, where the loggers applied it to the light wood of white pine, a conifer. The term was applied to all conifers, regardless of their wood density.
   • Hardwood was the term given to hard maple, a dense wood, and thereafter to all deciduous species.
     
     
2. Wood can readily be identified as a hardwood or softwood by the presence or absence of pores when viewed in a transverse section.
   • If no pores are present, the section is softwood. Pines show small, fairly evenly distributed resin ducts on a transverse surface. Resin ducts should not be confused with the pores in hardwoods. The pores in hardwoods are closer together than are the resin ducts in softwoods.
     
     
3. When the wood from a conifer is viewed from the top, in transverse section, tracheids or water carriers, form the bulk of the wood surface.
   • Between the various cells is a cementing substance called the middle lamella.
     Springwood (formed in the spring) cells are distinguished by their larger size from the smaller summerwood (formed in the summer) cells. Together the springwood and summerwood cells make up the annual ring, which is added to the tree each year.
     • Certain chemicals can be used to dissolve the middle lamella, remitting the fibers to be separated. A process used in making paper.
   • When the wood is viewed in a vertical plane, medullary rays will be seen and their function is to store food and distribute it horizontally. There are two types of rays: fusiform medullary rays and rays with horizontal resin ducts.
   • Softwoods use fibers to transfer sap. Simple pits are unthickened portions of cells walls through which sap passes from ray cells to fibers, or vice versa. Bordered pits on the surface have their margins overhung by the surrounding cell walls.
     
     
4. Hardwoods have specialized pores or vessels for conducting sap. The pores in hardwoods vary in size depending on the species. Some are visible to the naked eye.
   • Hardwood vessels are cells with open ends, one above the other, and continuing as open passages for long distances. In the heartwood and sapwood of some species, the pores are filled with tyloses, which is an organic material that is extruded into tracheids and pores of trees from adjacent parenchyma cells. Parenchyma cells are thin-walled structures that participate in the metabolism and storage of sugars.
   • The strength giving elements of hardwood are called wood fibers. Usually wood fibers have small cavities and thick walls. Pits are found in the fiber walls, which allow the sap to pass from one cavity to another.

What are two distinct anatomical features that distinguish hardwoods from coniferous species?

1. Hardwoods possess vessels (commonly called pores) when viewed in a transverse section.
   • If no pores are present, the species is a softwood or conifer.
     
     
2. Some conifers, such as southern yellow pine, show small, fairly evenly distributed openings called resin ducts on a transverse surface.
   • They appear as small. Light areas in the dark summerwood. 
   • The pores in hardwoods are closer together than are resin ducts.

Read Mississippi State University Extension Service's Basic Guide to Identification of Hardwoords and Softwoods for more information.

Read Distinguishing Softwoods from Hardwoods.

You will be reading about the difference between softwood and hardwood. Use this opportunity to develop an understanding of the difference between the trees.

What are some examples of hardwood and softwood trees?

Just a few examples of each are: