- the fact of having unequal physical properties along different axes:Even crystals with a simple cubic lattice structure, such as salt, display optical anisotropy; that is, the light propagates differently in different directions.
- the fact of having different rates of growth in different directions:Anisotropy is a nearly ubiquitous feature of plant growth; it is necessary, if a growing plant organ is to produce any other form than a sphere.
