Involved in lignin biosynthesis. May catalyze the final step specific for the production of lignin monomers, like coniferyl alcohol, sinapyl alcohol and 4-coumaryl alcohol. (E)-cinnamyl alcohol + NADP(+) = (E)-cinnamaldehyde + H(+) + NADPH Binds 2 Zn(2+) ions per subunit. Aromatic compound metabolism; phenylpropanoid biosynthesis. Homodimer. Expressed in the vasculature of the primary root and elongation regions. Expressed in the hypocotyl, cotyledon veins, vasculature of the first rosette leaves, and hydathodes. In stems, expressed in the vascular cambium, interfascicular cambium, developing xylem, and phloem. Expressed in the entire floral organs at late developing stage, and in the abscission, style and stigmatic regions of siliques and seed funicules. Belongs to the zinc-containing alcohol dehydrogenase family.