Wood Anatomy of Thuja sutchuenensis Endemic to China

The wood anatomy of Thuja sutchuenensis,an endangered plant endemic to China,is observed for the first time under optical and scanning electron microscopes.Growth rings are delineated by a narrow darker band of thick-walled latewood tracheids with abrupt transition from earlywood(EW)to latewood(LW).Longitudinal tracheids are relatively short with an average value of 1.61±0.22 mm in EW tracheids and 1.74±0.26 mm in LW tracheids.The bordered pits are mostly uniseriate,warty layer occasionally occurred on the pit margo.Cross fields are predominantly taxodioid with 2-6(8)pits.Xylem rays are mostly uniseriate with 1-11(2-5)cells in height and 65-70 rays per mm² in density,among which nodular and indenture structure is apparent.The observation shows that the main characters of T.sutchuenensis wood are similar to those in other four species of this genus,providing evidence for the further investigation of T.sutchuenensis.