Hardwood.html



Beech is a typical temperate zone hardwood

SEM images showing the presence of pores in hardwoods (Oak, top) and absence in softwoods (Pine, bottom)

The term hardwood is used to describe wood from broad-leaved angiosperm trees. In temperate and boreal latitudes they are mostly deciduous, but in tropics and subtropics mostly evergreen. Hardwood contrasts with softwood, which comes from conifer trees. On average, hardwood is of higher density and hardness than softwood, but there is considerable variation in actual wood hardness in both groups, with a large amount of overlap; some hardwoods (e.g. balsa) are softer than most softwoods, while yew is an example of a hard softwood. Hardwoods have broad leaves and enclosed nuts or seeds such as acorns. They often grow in subtropical regions like Africa and south-east Asia, but also in temperate regions such as Europe and North America. The dominant feature separating hardwoods from softwoods is the presence of pores, or vessels. ¹ Examples of European hardwoods from evergreen trees include holly (Ilex aquifolium), boxwood from Buxus sempervirens and oak from the holm oak Quercus ilex. Common deciduous European and North American hardwood species include the oaks (Quercus species), beech (Fagus species), ash (Fraxinus species), maple (Acer species) and cherry (Prunus species). Important tropical hardwoods include teak (Tectona), mahogany (Swietenia), iroko (Chlorophora excelsa), ebony (Diospyros ebenum) and rubberwood (Hevea brasiliensis).

Hardwood species are more varied than softwood. There are about a hundred times as many hardwood species as softwoods. The vessels may show considerable variation in size, shape of perforation plates (simple, scalariform, reticulate, foraminate), and structure of cell wall (e.g. spiral thickenings).

Hardwoods are employed in a large range of applications including: construction, furniture, flooring, utensils, etc.

Solid hardwood joinery is expensive compared to softwood. In the past, tropical hardwoods were easily available but the supply of some species such as Burma teak and mahogany is now becoming restricted due to sustainability issues^{citation needed}). Cheaper "hardwood" doors, for instance, now consist of a thin veneer bonded to a core of softwood, plywood or medium-density fibreboard (MDF).

See also

• List of woods
• Softwood
• Wood flooring
• Janka Wood hardness rating

References

Further reading

• Schweingruber, F.H. (1990) Anatomie europäischer Hölzer—Anatomy of European woods. Eidgenössische Forschungsanstalt für Wald, Schnee und Landscaft, Birmensdorf (Hrsg,). Haupt, Bern und Stuttgart.
• Timonen, Tuuli (2002). Introduction to Microscopic Wood Identification. Finnish Museum of Natural History, University of Helsinki.
• Wilson, K., and D.J.B. White (1986). The Anatomy of Wood: Its Diversity and variability. Stobart & Son Ltd, London.

!

External links

• Center for Wood Anatomy Research
• Hardwood Information Chart