Polynucleotides encoding polypeptides that increase the secondary growth of plants were identified. Introduction of the polynucleotides into plants produces plants having altered characteristics, such as increased secondary growth, increased phloem production, increased xylem production, increased number of internodes, and/or increased stem diameter. Expression of the polynucleotides in plants in the antisense orientation may produce plants that have decreased secondary growth, decreased phloem production, decreased xylem production, decreased numbers of internodes, and/or decreased stem diameter.
