Thank you for helping us improve the quality of Unity Documentation. Although we cannot accept all submissions, we do read each suggested change from our users and will make updates where applicable.
CloseUnity comes with a few trees in the standard assets (menu: Assets > Import Package > Terrain Assets) and can import trees created with standard 3D modelling software. However, Unity also provides a Tree Creator tool that lets you design trees directly within the editor. This is very useful when you want to create detailed forests and jungles with different tree types and variations.
This section of the manual explains how to use the tree creator. Since many projects do not require trees, the tree creator is supplied as a optional package that you must import before using it (menu: Assets > Import Package > Tree Creator).