Ray properties in the stems of Dahurian larch (Larix gmelinii) and Japanese larch (Larix kaempferi)

The radial variation of rays within the stems of Dahurian larch and Japanese larch growing in Korea was studied to obtain valuable information to identify the two species and determine wood quality. Uniseriate ray height, fusiform ray height, ray number, ray spacing, and epithelial cell number were investigated by optical microscopy. The heights of uniseriate and fusiform rays and epithelial cell numbers in Dahurian larch were lower than those in Japanese larch. Dahurian larch wood had greater ray number and ray spacing than Japanese larch wood. In both species, the heights of uniseriate and fusiform rays and epithelial cell number increased with increasing growth ring number but then stabilized from a certain growth ring number. However, ray number and ray spacing decreased with age but were stable toward the bark. There were significant differences in all ray properties between the two species. Furthermore, in both species, the number and spacing of rays showed a significant negative correlation with uniseriate ray height. The relationships between uniseriate and fusiform ray height, and between ray spacing and ray number were significantly positive. In conclusion, the results from this study provide basic information that can be used to identify these species, and the quality indices from ray properties will improve the effective utilization of the two woody species.