Most of us are familiar with the external appearance of a tree, and you’ve probably seen the rings visible on the inside when a tree is cut. Children enjoy counting these rings to determine the tree’s age, but the anatomy of a tree involves much more than just the rings and outer bark.
Trees consist of five main sections: the pith, heartwood, sapwood, cambium, and bark. The pith is the central core of the tree and represents its original stem. Surrounding the pith is the heartwood, which is older, inactive wood. It is usually darker and denser than the sapwood. The sapwood encompasses the outer 4-20 rings and is the living part of the tree responsible for transporting water and nutrients.
The cambium is the layer situated between the bark and the sapwood. It plays a vital role in increasing the tree’s diameter and responds to external damage by growing calluses to facilitate repair. Lastly, the bark forms the outermost protective layer of the tree. While the outer bark is lifeless, the inner layer of bark is alive and functions to transport nutrients throughout the tree.
Growth Rings
Have you ever paused to consider the function of the rings when counting them on a tree? These annual rings actually consist of large pores that play a crucial role in transporting water to the leaves. Visualize them as vertical cylinders. Additionally, the medullary rays, which run perpendicular to the annual rings, further aid in delivering nutrients and sap to the inner layers of the tree.
If you examine a tree stump or the cut end of a tree, you’ll be able to observe both the growth rings and the medullary rays, also known as pith rays. These rays appear as light-colored ribbons radiating from the center of the tree. You may have noticed these lines in a quarter-sawn wood floor, which is appreciated for its beauty and character largely due to the presence of medullary rays.
Early Wood, Late Wood
Early wood, as the name suggests, refers to the wood that grows during the spring, while late wood is the wood that grows in autumn and winter. Late wood tends to be denser than early wood, and its grain patterns often appear darker, reflecting the characteristics of the growth season. These changes in grain patterns serve as a reliable indicator of the season in which the wood developed, with distinct seasonal patterns being observable.
Softwood and Hardwood
Not all woods used in homes are hardwoods; some, like pine or fir, are categorized as softwood. Softwood comes from conifer trees, which are evergreen needle-bearing trees that retain their leaves throughout the year. Common examples of softwood trees are spruce, cedar, pine, and Douglas fir. On the other hand, hardwood trees are broad-leafed and go dormant in winter. Deciduous trees such as oak, maple, ash, and cherry shed their leaves during fall and grow new ones in spring.
However, the classification of wood as softwood or hardwood doesn’t solely rely on its density. Some softwood trees actually have harder wood than certain hardwood trees. To measure the density or hardness of wood, the industry uses the Janka scale. This scale provides a standardized way of evaluating and comparing the hardness of different wood types.
The most common species in North America
In North America, there are seven tree species commonly used for wood flooring. Among these, oak stands out as the most prevalent choice. Oak trees are abundant in both Red Oak and White Oak varieties. Red oak exhibits a red-brown or pinkish hue and features an open-grain pattern. In contrast, White Oak appears light-brown with longer grains and more noticeable rays.
To ensure sustainability and preserve the forests, red and white oak trees are typically harvested after 40 years of growth. However, most oak trees in the US are allowed to mature until they reach 60 years old before being cut. This practice not only protects the environment but also ensures a surplus of inventory for the wood flooring industry.
Another popular wood flooring option is Maple. With nearly 150 subspecies available, Maple flooring finds common use not only in gyms but also in residential spaces. Its light color and closed grain pattern contribute to its appeal.
Hickory, known for its exceptional density, is a highly durable flooring choice, which also makes it popular for tool handles. The color variation in hickory flooring can be quite wide, ranging from tan and brown to red and cream-colored.
Cherry is yet another common wood flooring option. Besides being used for flooring, it enjoys popularity in crafting musical instruments and furniture. Its fine, uniform grain and rich color add to its desirability, and it can vary from light to dark red-brown in appearance.
Walnut stands out as one of the darkest floors on this list, boasting a beautiful dark brown color that may showcase black streaks. Its straight open-grain pattern can sometimes feature burled or curly character in certain spots, adding to its allure.
Ash is another sought-after flooring type, known for its calico grain pattern with tan and dark brown streaks. It can display both straight and bold grains, as well as wavy figuring, creating a distinctive appearance. Beyond flooring, Ash is commonly utilized in crafting pool cues, baseball bats, and rowing oars.
Lastly, Pine remains a popular wood species in North America. Among the common choices for flooring are Antique Hard Pine and Southern Yellow Pine. Antique Pine boasts a denser grain and darker color, while Southern Yellow Pine exhibits plenty of character and a closed grain pattern, making it equally appealing for flooring applications.
Indeed, the anatomy of a tree is far more intricate than what meets the eye from its external appearance. The internal structure of a tree can vary significantly depending on factors such as the species, the environment in which it grows, and other environmental influences. By delving into the intricacies of grain patterns, diverse wood types, and other distinctive characteristics, one can gain valuable insights that aid in accurately identifying the species and grade of a wood floor. This deeper understanding enhances precision and ease when working with wood flooring materials.