Willow plants like Salix viminalis grow quickly and produce a lot of wood every year. This wood can be cut and burned as a type of renewable energy called "green fuel". There are many different types of willow plants, with over 400 species in the world. Some of them have unique names like Sageleaf Willow or Furry Willow. Willows can easily mix and create new types of plants through natural processes or human cultivation. This study provides a detailed classification of different willow species.