To many people, wood is the quintessential building material for furniture, both indoor and out. There's a wooden furniture form to suit every budget and dcor -- from rustic twig loveseats to classis cedar Adirondack chairs to sophisticated teak tables and benches.

In fact, the varieties of wood are dizzying. Which should you choose? How should you care for it? And is wood an environmentally-friendly choice for outdoor furniture?

Types of Wood

First, understand that hardwood is not necessarily hard and softwood is not always soft. The terms refer simply to the type of tree from which the wood is obtained: hardwood from broad-leafed trees, and softwood from needle-bearing trees.

All wood outdoor furniture may be cleaned with warm water and mild detergent.

Here are the most common types of wood used in the construction of outdoor furniture.

• Redwood is a durable hardwood, grown on the west coast of North America (the Coast redwood) and in China (the Dawn redwood.) Redwood is straight-grained with a reddish color, and has a high resistance to termites and rot. Treated properly, it can last more than 25 years.

The redwood harvested in North American is cut mainly from private lands that are zoned for timber use. Over 95% of these areas are previously harvested -- that is, they are not virgin, old-growth forests. The Coast redwood can grow to 130 feet in just 30 years.

• Cedar is a North American softwood, light in color and naturally splinter free. It resists insects, mold, mildew and decay, and it weathers well. With proper care, it can last 25 years. Since cedar is a quick grower, it's a resource that renews relatively rapidly.

• Teak is perhaps the most coveted of outdoor furniture woods and with good reason. It's a honey brown hardwood that is highly resistant to rot and decay and will last 50 years or longer, even if left outdoors year-round. Teak is now harvested primarily from plantations in Southeast Asia. Dwindling stocks and high consumer demand have combined to make the price of teak soar.

The high price of teak has made other tropical hardwoods, such as roble, shorea, jarrah and eucalyptus popular. All of these woods are dense, durable, and stand up well to weather.

• Jarrah, which is reddish or pinkish, is harvested in Australia from government-managed forests to ensure reforestation.

• Shorea, grown in Indonesia and Malaysia, is stronger and heavier than teak but because of the large quantity available, is usually priced lower. Both jarrah wood and shorea will last up for up to 50 years.

• Roble is a golden, relatively lightweight hardwood harvested mainly from dry tropical forests in South America. It will last up to 25 years.

• Tropical eucalyptus is a native of Australia and is prized for its resistance to rot and handsome look. It also will last decades.

Tropical hardwoods will weather to a silvery finish over time, unless treated twice a year with teak or other furniture oil.

• Pine is an affordable softwood that is harvested in many varieties from various parts of the world, but especially from American forests. All are yellow color with brown knots and are excellent for staining. Pressure-treated pine will last for 20 years but untreated, pine has low rot-resistance. It should be painted, stained or sealed and stored indoors during the winter.

• Willow, cypress, alder and other trees with pliable branches are used for bent-twig furniture. Willow is especially renewable as when it is cut, two or more shoots will grow out of the stump of the cut piece. Harvested properly, willow will continue to grow cutting after cutting.

If you use twig furniture outdoors, spray or brush on a good quality clear exterior varnish and use the furniture only in a protected area.

Is It Environmentally Friendly?

The Forest Stewardship Council (FSC) certifies lumber forests around the world, although only a small percentage of the lumber produced globally is FSC certified. If you are extremely concerned about the future of the world's wood supply, look for an FSC label on the underside of the furniture piece or on the hanging tag.

If you are not so stringent in your views, you may wish to consider furniture made from wood harvested from responsibly government-managed forests or from plantations, which grow trees much like farms grow other crops. In addition, according to the Hardwood Manufacturers' Association, harvesting levels of American hardwood are far below the levels of growth, so that twice as much hardwood grows each year as is harvested.

Alternatively, you may choose to purchase furniture made from reclaimed wood - that is, wood that was previously used for consumer items and that has been refashioned into new furniture. In addition, some companies offer recycled wood furniture-furniture made of recycled pallets or barn wood. You can find a partial listing here http://www.ecobusinesslinks.com/links/recycled_green_furniture_manufacturers.htm

When considering the ecological impact of purchasing wooden furniture, you should also look at the lifespan of the wood. Most wooden pieces last decades -- more than long enough for the wood's source to be renewed.

So, whether you go rustic or elegant, wood may well be a wise choice for your outdoor furnishings. Take a seat -- and relax!