Abstract
"Tawarasibo" is an uneven thickening, specific to Japanese cypress , producing the special undulation of trunk surface which looks like piled-up barrels, or Japanese rice boles ("Tawara" in Japanese). Trees with this special trait had been rarely found in artificial plantation, and prized as an alcove post. Some mutations may be involved in this trait; no systematic observations had been made on the course of the expression of this trait. Xylem anatomy of a "tawarashibo" clone is reported here. Sample blocks were cut out from both abnormally thickened region and normal region. Transverse, tangential, radial sections were observed by photo microscopy and scanning electron microscopy (SEM). At the radial section of the thickening region, conspicuous disturbance of radial arrangement of tracheid, anastomosis of tracheid, trabeculae were observed. However, the irregular arrangement soon calms down at the outer side. At the tangential section, the disturbance of cell arrangement is not so severe as the radical arrangement. These observations may be suggest that the abnormal arrangement occurred in the course of cell maturation and enlargement and the cambial cells are not harmed during the abnormal thickening. This may be suggesting the genetic deficiency, which controls cell enlargement and cell wall construction.
