Read the following text and answer the question.

Source: pinterest.com

There are trees that gardeners work hard to keep tiny. If trees were left in nature, they would grow tall. But these trees are kept small by the skills of the gardener. Gardeners with these skills practice the Japanese art of bonsai.

Bonsai comes from the Japanese words "bon" (meaning pot) and "sai" (meaning plant). A gardener who practices bonsai makes sure that a tree does not grow too tall or wide. The trunk and branches are trimmed a little at a time. Small trims are necessary so that the tree does not die. Too much trimming, or cutting off a vital branch or root, can hurt a plant.

Bonsai gardeners work for years to prune and shape each tree. A bonsai tree that is carefully tended can grow for hundreds of years. The bonsai is passed from one gardener to another. It takes many years to develop the skills of a bonsai gardener.

Adapted from: readworks.org

Which of the following is not described in the text?