latewood

Latewood, in tree ring anatomy, is the portion of the annual ring formed later in the growing season. It typically develops from late summer through early autumn and is usually darker in color than earlywood. Latewood cells are generally smaller with thicker cell walls, leading to higher wood density.

In conifers, latewood comprises densely packed tracheids with thick walls and small lumens, contributing to the ring's denser band. In many hardwoods, latewood contains smaller vessels and thicker-walled fibers; the boundary between earlywood and latewood can be abrupt or gradual and is influenced by climate and growing conditions.

The relative amount of latewood within a ring, often expressed as latewood proportion, affects mechanical properties such as density, stiffness, and shrinkage. It is a key parameter in wood quality assessment and in dendrochronology, where latewood density and width improve climate reconstructions. Environmental factors such as temperature and moisture availability regulate latewood formation.