(1) The tax levied in this part does not apply to an unauthorized substance in the possession of a merchant who is authorized by law to possess the substance. This exemption applies only during the time the merchant's possession of the unauthorized substance is authorized by law.
(2) The tax levied in this part does not apply to the following marijuana: Harvested mature marijuana stalks when separated from and not mixed with any other parts of the marijuana plant;
(3) Fiber or any other product of marijuana stalks described in subdivision (b)(1), except resin extracted from the stalks;
(4) Marijuana seeds that have been sterilized and are incapable of germination; or
(5) Roots of the marijuana plant.