Unkraut German for pest plants - is natures opposition to the leadership of gardeners.Unkraut is an every day term used to describe a plant considered undesirable. The word—commonly applied to unwanted plants in human-controlled settings, such as farm fields, gardens, lawns, and parks—carries no botanical classification value. Indeed, a number of plants that many consider Unkraut are often intentionally grown in gardens and other cultivated settings.The definition of Unkraut is very much in the eye of the beholder. Some plants are generally viewed as Unkraut. That's wrong, because the same species can be a medical herb or a useful plant.