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How do earlywood and latewood differ in cell size and wall thickness?
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Temperate softwoods (left column) and hardwoods (right column), selected to highlight natural variations in colour and figure: (A) Douglas fir, (B) sugar pine, (C) redwood, (D) white oak, (E) American sycamore, and (F) black cherry. Each image shows (from left to right) transverse, radial, and tangential surfaces. Click on an individual image for an enlarged view.
Earlywood and latewood differ significantly in their cellular structure, which creates the visible patterns known as growth rings in wood.
- Earlywood: Formed at the beginning of the growing season, earlywood is characterized by larger cells with thinner walls. Because these cells have larger diameters, they are less dense and facilitate more rapid water conduction.12
- Latewood: Formed later in the season, latewood consists of cells that are smaller in diameter and possess thicker walls. These thicker-walled cells generally mark the end of a growth ring.12
In many species, particularly conifers and ring-porous hardwoods, this contrast in cell size and wall thickness creates a clear demarcation between the latewood of one year and the earlywood of the next. While diffuse-porous trees maintain more uniform vessel sizes throughout the season, the general trend of decreasing cell diameter and increasing wall thickness toward the end of the growth period remains a fundamental aspect of wood formation.123