California Code, Health and Safety Code - HSC § 14875

(a) Vegetation that bears seeds of a downy or wingy nature.

(b) Vegetation that is not pruned or is otherwise neglected so as to attain such large growth as to become, when dry, a fire menace to adjacent improved property.

(c) Vegetation that is otherwise noxious or dangerous.

(d) Poison oak and poison ivy when the conditions of growth are such as to constitute a menace to the public health.

(e) Dry grass, stubble, brush, litter, or other flammable material which endangers the public safety by creating a fire hazard in an urbanized portion of an unincorporated area which has been zoned for single and multiple residence purposes.