Rays may contain both parenchyma & tracheid cells

In some conifers wood rays are heterocellular, i.e. they contain cells of two types, ray parenchyma and ray tracheids. The ray tracheids are marginal cells of the rays and are distinguished from the ray parenchyma cells by the presence of bordered pits.

Shown here is a radial section of a ray in the early wood of eastern white pine (Pinus strobus).

1 = tracheid, 2 = ray parenchyma, 3 = bordered pit, 4 = ray tracheid