Origin and Development of Fascicular Cambium in Hypocotyl of Eucommia ulmoides Seedlings

두충나무 유식물의 하배축에서의 유관속내 형성층의 기원 및 발생

The early ontogeny of the vascular cambium in the hypocotyl of Eucommia ulmoides seedling was studied anatomically. In transverse view, the procambial cells repeated periclinal divisions and then gradually differentiated into vascular cambium; however, in the transectional plane, it was difficult to reveal the origin of cambial initials. In tangential view, the early procambial cells repeated periclinal divisions and then the procambium consisted of homogeneous short cells. Some cells in late procambium did not show transverse divisions, but elongated continuously. Thus, the procambium showed a heterogeneous structure: The long cells became fusiform initials with tapering end walls and the short cells differentiated into ray initials. Conclusively, the two types of cambial initials were gradually originated from the homogeneous cells at the early procambial stage, and they consisted vascular cambium.