by Eric Meier ©
In sharp contrast to the simple anatomy of softwoods, the hardwoods of the world exhibit a dazzling array of endgrain patterns and intricate motifs; and it’s in this complexity that the challenge (and joy) of wood identification really comes alive. An unknown hardwood sample could be just about anything under the sun, yet as each anatomical feature is considered, anything is narrowed down to something.
That is to say, throughout the identification process, the more observations that can be made and classified about a hardwood sample, the more and more the field of possible candidates narrows. Ultimately, the point is reached where no further refinements can be recorded, and either a clear identification emerges, or a handful of possibilities remain.
As discussed on the page The Truth Behind Wood Identification, a positive identification down to the species level isn’t always possible, but generally, anything can be narrowed down to a more descriptive something, and in many cases, the genus or family of the wood can usually be ascertained. To begin this process, the largest and most conspicuous anatomical elements are examined first.
In a living tree, the parenchyma contained in the sapwood consists of living tissue that serves as storage cells. Technically, there are a few different types of parenchyma cells seen in wood, (such as those occurring radially in the rays), but far and away the most common type of cells that are designated specifically as parenchyma refer to longitudinal or axial parenchyma, which are oriented along the length of the tree-trunk. All references to parenchyma in this website will be describing axial parenchyma.
Single parenchyma cells are typically too small to be seen individually, but when viewed as a whole, patterns and shapes emerge. Very infrequently, parenchyma is absent or hardly observable, but in most hardwood species, parenchyma forms unique and telling patterns that greatly aid in the identification process. In describing parenchyma, there are two main classifications.
Found on practically every wood species, rays can ofttimes serve to provide valuable clues in the identification process. In a living tree, these cells actually run perpendicular to the rest of the wood fibers, and serve to channel nutrients between the cambium, sapwood, and pith. When viewed from the endgrain, rays appear as more-or-less straight, radial (vertical) lines spaced evenly across the wood sample.
In a living tree, hardwood fibers have strong, thick cell walls that mainly serve to support and strengthen the trunk. When viewed from the endgrain, fibers are very small and can’t be seen individually. Instead, fibers can only be distinguished in a broader sense as colored areas which form the backdrop of the wood’s endgrain.
Occasionally, the wood fibers will change in color in correlation with the growing season, providing a means to distinguish the growth ring boundaries in instances where it may not be apparent in the arrangement of pores or marginal parenchyma.
Hardwoods are classified as dicotyledons, (or “dicots” for short) because they have two cotyledons (embryonic leaves). That is to say, when a dicot first emerges from its seed, the seedling will have two leaves. Most of the world’s fruits, vegetables, and fibers are dicots.
However, within the division of Angiosperms (flowering plants) there are also plants that only have one embryonic leaf, called monocotyledons, or “monocots” for short. This important group contains corn, wheat, rice, and all true grasses. In the woodworking world, the most notable monocots are palm and bamboo.
Anatomically, the “wood” of monocots is diverse from both hardwoods and softwoods, and can usually be spotted easily, even without magnification. Viewing the endgrain reveals a fairly simple structure of darker-colored fibrovascular bundles embedded throughout a mass of lighter-colored parenchyma cells. Growth rings, sapwood/heartwood, and rays are all completely absent.
Narrowing most monocots down to even the genus level (let alone to a precise species) is essentially impossible—at least when limited to the anatomical features of the wood itself. There just aren’t enough distinguishing features present to discern between different species. Fortunately, in woodworking and lumber applications, there are generally only a few types of monocots encountered.