Because wood color is an important quality characteristic in black walnut (Juglans nigra L.), a study was devised to examine some cellular features of heartwood coloration using microspectrophotometric techniques. Five commercially prepared veneer samples exhibiting low macro-luminance (darker) and five exhibiting high macro-luminance (lighter) were chosen for microscopic color analysis. Statistically significant differences were found between the high and low macro-luminance sample groups in the micro-luminance color value in some cellular features (axial parenchyma walls, ray parenchyma walls, fiber walls, and ray parenchyma inclusions). Also observed were large differences in the dominant wavelength of ray parenchyma inclusions between the sample groups. These results suggest that quality of these coloration pigments (phenolics) is more important than quantity for overall color variations
