The Legislature hereby declares that by making any additions to or amendments of this chapter it intends to formulate a system of grades and standards and minimum requirements for nursery stock to the end that purchasers of nursery stock may have adequate knowledge concerning the name and the grade size of nursery stock with relation to established standards. If, however, any provisions of, or amendment or addition to, this chapter, either as originally enacted or as amended or added to, should be held to be unconstitutional, the unconstitutionality of such provision shall not affect any other provision of this chapter.