Identifying the type of mint. Just to confuse the picture even more, there is a chocolate mint which has purplish stolons. There are, in fact, hundreds of varieties of mint, some of which are commercially grown for oil extraction or for leaf drying, and a lot of which haven't even been given names, being known as Mint 341, etc.
Simply put, watercolor is a painting compound using water-soluble pigments that are either transparent or opaque. Because of the medium itself as well as the paper to which it is applied, watercolor is frequently thought of as a fugitive medium.
Gouache is a type of paint, and its main appeal is that it is water-based. Other than that, it is very similar to acrylics. However, the fact that it's water-based renders it different uses than acrylics.