Abstract: Mechanical injury to the exposed surface of the girdled trunk of Eueommia ulmo- ides Oliv. was conducted by scraping frames 10×l0 cm2 in four varieties of shapes, i.e. ∪、| |、Π and □ The scraping edge was 2 cm in width and 1 mm in depth. One month after treatment, periderm was formed at the central portion of all the scraped areas, however, among them the thickness, degree of differentiation and starch distribution of the regenerated bark were different. The newly-formed bark of the ∪ -shaped area was the thickest, and vascular cambium-like meristem was formed in the central portion which later gave rise to vascular tissues. The thickness of the newly formed bark in Ii -shaped area was half as :thick as the former, although similar tissue differentiation was observed. The thick- ness of the newly-formed bark inΠ-shaped area was half of that in∪ -shaped area. The flat meristematic cells were only seen in the deeper layer, and no vascular tissues were visible. The thickness of the newly-formed bark in the □ -shaped area was only 1/4 of that in ∪ -shaped area. There were undifferentiated parenchyma cells below the periderm in which very few flat meristematic cells were formed later.

Key words: Eucommia ulmoides, Regenerated bark