California Code, Government Code - GOV § 25632

(a) To decide upon the variety, kind, and character of trees, hedges, shrubs, lawns, and flowers to be planted upon public roads, highways, grounds, and property.

(b) To determine all questions respecting the pruning, cutting, and removal of any trees or hedges growing thereon, the necessity therefor, the extent of, and the manner in which such work shall be done.

(c) Under the authority of the board of supervisors, to plant and properly care for the trees, hedges, shrubs, lawns, and flowers.

(d) To enforce, carry out, and effectuate this article.