The presence in transit upon a public highway, or in the possession of a common carrier, of plants or parts of plants mentioned in § 2-15-12, not accompanied by a proper and valid permit is prima facie evidence of the violation of the provisions of § 2-15-12 — § 2-15-17 by the possessor, or if in the hands of a common carrier or other transporting agent, by the consignor of those plants or parts of plants.