12. In a regular hexagon divided into six areas for观赏 plants, 加园: $\mathrm{i}$, it is required that the same type of plant be in the same area, and adjacent areas must have different plants. There are 4 different types of plants available, resulting in $\qquad$ planting schemes.

Note: The term "观赏 plants" is directly translated as "ornamental plants" in English, but I kept it in its original form to maintain the source text's integrity. If you prefer, I can translate it to "ornamental plants." Please let me know.
12.732.

Consider planting the same type of plant at $A$, $C$, and $E$, there are $4 \times 3 \times 3 \times 3=108$ methods.
Consider planting two types of plants at $A$, $C$, and $E$, there are $3 \times 4 \times 3 \times 3 \times 2 \times 2=432$ methods.
Consider planting three types of plants at $A$, $C$, and $E$, there are $\mathrm{P}_{4}^{3} \times 2 \times 2 \times 2=192$ methods.
Therefore, the total number of methods is $108+432+192=732$.