The only way to get straight material would be to split it out.
It is for this reason that split billets and squares are stronger than most sawed material.

The presence of the spiral grain has little, if any, effect on the timber when it is used in the round, but in sawed material the greater the pitch of the spiral the greater is the defect.
KNOTS _Knots_ are portions of branches included in the wood of the stem or larger branch.

Branches originate as a rule from the central axis of a stem, and while living increase in size by the addition of annual woody layers which are a continuation of those of the stem.

The included portion is irregularly conical in shape with the tip at the pith.

The direction of the fibre is at right angles or oblique to the grain of the stem, thus producing local cross grain.
During the development of a tree most of the limbs, especially the lower ones, die, but persist for a time--often for years.
Subsequent layers of growth of the stem are no longer intimately joined with the dead limb, but are laid around it.