Quercus kelloggii, also known as California Black Oak or Kellogg Oak, is a native oak tree in western North America. It can grow in various types of soil, but well-drained soil is crucial. The tree is known for its large acorns and deeply lobed leaves, and its bark becomes thick and plate-like with age. California Black Oak is a vital species for wildlife, providing food and cover for many animals, including livestock. The tree is also used for making furniture, pallets, and construction timber. Nowadays, it is cultivated as an ornamental tree in native plant, drought tolerant, water-conserving, and habitat gardens. Quercus kelloggii comprises a total volume of 29% of hardwood timber resources in California and is the major hardwood sawn into lumber there. However, the species has decreased from its historic abundance due to drought, disease, animal foraging, logging practices, fire suppression, and human impacts. It is important to protect and conserve the California Black Oak as a critical species for wildlife and a valuable hardwood resource.