Wood cuts
The angle at which a board is cut determines how the finished product looks. Wood flooring is either plainsawn, quartersawn or riftsawn. Below Floors in California describes the various types.

Plainsawn

Plainsawn is the most common and least expensive method of wood flooring cuts. Plainsawn however, contains more variation than the other two cuts because grain patterns resulting from the growth rings are easier to see. This is the most economical way to produce flooring because it creates the widest boards with the least amount of waste. Plainsawn is considered by some less dimensionally stable than other cuts.

The flooring will tend to expand and contract more across the width of the boards.

Quartersawn

Quartersawing, the most expensive, produces less board feet per log than plainsawing. The log is first cut into quarters and then sawn perpendicular to the growth rings. Quartersawn wood twists and cups less, wears more evenly and is considered the most stable. Because of how it is cut, when quartersawn flooring is introduced to changing climates and humidity, the wood expands and contracts vertically instead of horizontal. Quartersawn flooring is a most ideal choice for installs that are over radiant floor heating, as recommended by the National Wood Flooring Association and Floors in California.

Riftsawn
Riftsawn is most similar to quartersawn, except the cuts are made at a different angle.