California Code, Health and Safety Code - HSC § 11018.5

(a)(1) “Industrial hemp” or “hemp” means types of the plant Cannabis sativa Linnaeus or any part of that plant with a total tetrahydrocannabinol concentration of no more than 0.3 percent on a dry weight basis and is limited to only agricultural products, including seeds, propagated plant material, immature or mature plants, harvested plants, mature stalks of the plant, fiber produced from the stalks, oil or cake made from the seeds of the plant, or any preparation that does not contain cannabinoids.

(2) Total tetrahydrocannabinol concentration includes both delta-9 tetrahydrocannabinol and tetrahydrocannabinolic acid, and shall be calculated using the following equation:  Total THC concentration (mg/g) +/- the measurement of uncertainty, as defined by the Department of Food and Agriculture.