Involved in lignin biosynthesis. Catalyzes the final step specific for the production of lignin monomers. Catalyzes the NADPH-dependent reduction of coniferaldehyde, 5-hydroxyconiferaldehyde, sinapaldehyde, 4-coumaraldehyde and caffeyl aldehyde to their respective alcohols. (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, hydathodes and at the base of the trichomes. In stems, expressed in the vascular cambium, interfascicular cambium developing xylem and cortex region. Expressed in the style, the vascular strands of the sepals pollen and anthers in flowers, in the abscission and stigmatic regions of siliques and seed funicule and testa. Belongs to the zinc-containing alcohol dehydrogenase family.