Sweet gum, a widely recognized tree, often prompts questions regarding its classification as a hardwood. Botanically, sweet gum is indeed a hardwood. This classification is determined by the tree’s reproductive characteristics, not always its physical hardness, clarifying why some “soft” woods are botanically hardwoods and vice-versa.
Distinguishing Hardwood from Softwood
The fundamental difference between hardwoods and softwoods lies in their botanical origins. Hardwoods originate from angiosperm trees, which are flowering plants that produce seeds enclosed within a fruit or ovary. These trees typically feature broad leaves that are shed seasonally, like oak, maple, or walnut. Their cellular structure is more complex, often containing vessel elements (pores) that transport water and nutrients, visible as distinct grain patterns.
Conversely, softwoods come from gymnosperm trees, characterized by exposed seeds, often found in cones. These trees, such as pines, spruces, and cedars, generally have needles or scale-like leaves and remain evergreen throughout the year. While the terms “hardwood” and “softwood” suggest density, this is not always accurate. The presence or absence of pores is a key microscopic feature distinguishing the two.
Sweet Gum’s Botanical Classification
Sweet gum, scientifically known as Liquidambar styraciflua, is classified as a hardwood. This classification stems from its botanical nature as an angiosperm, meaning it produces enclosed seeds, typically found within its distinctive spiky, spherical fruits. The tree is deciduous, shedding its star-shaped leaves annually, further aligning it with hardwood characteristics.
The wood of sweet gum exhibits properties consistent with its hardwood classification. It is considered an intermediate-weight wood with an intermediate density. Sweet gum wood features a fine, uniform texture and its grain is often interlocked, which can create an attractive ribbon-stripe appearance when quartersawn. The heartwood, known as “redgum,” ranges from reddish-brown to darker streaks, while the sapwood, or “sapgum,” is lighter, appearing whitish to pinkish or tan.
Properties and Common Uses of Sweet Gum Wood
Sweet gum wood is suitable for various applications. It works well with hand and machine tools, and responds to turning, gluing, and finishing, readily accepting stains. Its moderate strength and intermediate weight contribute to its versatility in manufacturing.
Despite its workability, sweet gum wood presents some challenges, particularly during drying. It has a high shrinkage coefficient and a tendency to warp or distort if not dried carefully, often due to its interlocked grain. To mitigate this, proper stacking with closely spaced stickers and weighting of lumber piles are necessary. Common uses for sweet gum wood include veneer, plywood, furniture, cabinetry, and interior trim, due to its appealing grain patterns and ability to take finishes. It is also used for boxes, crates, and sometimes flooring, though its decay resistance is poor, making it unsuitable for outdoor applications.