A closer look at the gums

f, lthough they may grow side by flside in many swampy, lowland areas of the southern and eastern U.S., the gums are very different trees, and each produces two different types of wood.

Story at a Glance

American red gum's heartwood and sapwood marketed separately under different names, as are tupelo gum and black gum.

While most of the commercial production of American red gum (Liquidambar styraciflua) centers in the lower Mississippi Valley, the hardwood is found throughout the South and East. as well as in Mexico and Central America.

The tree grows from medium size to large, 80 to 100 ft. tall, with a long smooth bole of two to five feet in diameter. It grows best in low-lying land that is liable to flooding. The tree produces a vanilla-scented gum or resin, which was once used in medicine and perfume.

The heartwood and sapwood are marketed separately. The heartwood typically is sold as red gum, but also known in various areas as gum, sweet gum, southern gum, hazelwood, and in Britain, misleadingly, as satin walnut.

The well-defined heartwood is reddish-brown with a satin luster and dark streaks creating a mottled or marbled appearance. It has a fine, even, uniform texture and, in general, an irregular, interlocking grain that gives a striped figure to a quartered surface.

The heartwood is moderately heavy, about the same as soft maple, and, while not exceedingly strong, is

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its attractive figure. After seasoning, its average density is about 35 lbs. per ft. The wood has a very low steam bending rating and dries quickly with a strong tendency to warp and twist, so it requires great care in drying to avoid degradation. It is especially susceptible to atmospheric changes when in use and tends to shrink, swell, twist or split, often exceedingly, but quarter sawn boards are less liable to distort in service.

The wood works easily with both hand and machine tools, offering only slight resistance to cutting edges. It nails, screws, glues and stains well, and can be brought to a smooth, superb finish.

Non-durable, it is subject to insect attack. The heartwood is somewhat resistant to preservative treatment, but the sapwood is permeable.

Red gum is used both inside and outside the home, for less expensive furniture, doors, interior trim, joinery, cabinets, plus wooden dishes and fruit boxes. Supplies of veneer (sliced, rotary) are plentiful, with lumber available.

The sapwood is marketed as sap gum, but also identified in the United Kingdom as hazel pine. It is wide and creamy or pinkish white in color, often blued by sap stains. The pattern is weak, usually watery. Although similar to the heartwood in characteristics, it is not as durable.

It is used for interior plywood, furniture, including tv cabinets, and architectural woodwork. It is among the nation's most widely used species for veneer and is available in abundant quantities for both rotary veneer and lumber.

In the form of lumber, veneer and plywood this species is useful for a wide range of purposes, notably for furniture and interior woodwork, boxes, crates and pallets and dry cooperage. It is also used for pulp.

Tupelo, the other southern and eastern swamp tree, comes as tupelo gum (Nyssa aquatica), also called bay poplar or water tupelo, and black gum (Nyssa sylvatica), or black tupelo. Both are tall, growing up to about 100 ft., with a straight bole, a little larger than 2 ft. in diameter. but buttressed at the base.

Yellow to pale brown in color, the wood frequently has darker patches but is generally somewhat featureless. With a fine, even texture, it has indistinct annual rings and an irregular and often interlocked grain, which is tough and not inclined to split.

Years ago, the wood was troublesome due to its interlocking grain creating a tendency to warp or twist. But modern drying techniques and extra care have minimized these objections, and the species' workability rates good to excellent.

The wood is moderately light in weight, particularly tupelo gum, which tends to be softer and more open in texture than black gum. When swollen. wood from the tree's base may be exceptionally light.

Tupelo dries readily with a marked tendency to distort. It is not a strong wood, but black gum is noted for its resistance to splitting. Although soft and light, it is difficult to work and because of the irregular grain it takes care to produce a good finish. Durability is low in conditions favoring decay.

A general purpose wood used in the solid, it is often rotary-peeled for veneer and plywood. The better grades are used extensively by the furniture industry, while the lower grades end up in wirebound boxes and other shipping containers.

Other uses include interior joinery, fixtures, moulding, novelties, hardwearing flooring and pressure treated railway ties. It also is used as a plywood core veneer.