The ontogeny of the vascular cambium inGinkgo biloba roots |
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Authors: | Woong Young Soh Sung Sik Hong Duck Yee Cho |
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Institution: | (1) Department of Biology, Chonbuk National University, 560;(2) Department of Biology Education, Chonnam National University, 500 Kwangju;(3) Department of Biology, Chonju Woo-Suk University, 565-800 Chonbuk Samrye, Korea |
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Abstract: | Observation was made on early ontogeny of vascular cambium in the developing root ofGinkgo biloba L. After completion of root elongation, the vascular meristem gradually acquires cambial characteristics. Strips of the periclinal
division of cells in transverse section are observed on the inner side of phloem when the primary xylem and phloem in the
stele have been established. The strips are united into a continuous layer between phloem and xylem. In tangenital section,
the procambium shows a homogeneous structure, which is initially composed of short cells with transverse end walls and subsequently,
of long cells with tapering ends. Then, the procambium is organized into two systems of cells; axial strands of short cells
with transverse end walls resulting from the sporadic transverse divisions of long cells, and long cells with tapering ends.
Still later, the short cells are divided frequently in a trasverse plane exhibiting one or a few cells in width and several
decades of cells in height, while the long cells are elongated. The frequency of transverse divisions of the short cells decreases
in subsequent stages. Eventually, the short cells in axial strands are vertically separated from one another by the elongation
of neighboring long cells and by the decrease in the frequency of transverse divisions of short cells themselves. Cambial
initials occur in two forms; ray initials a few cells in height and one cell in width derived from the short cells, and fusiform
initials with tapering ends derived from the long cells. |
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Keywords: | Cambial initials Ginkgo biloba Homogeneous and heterogeneous procambial structure Root cambium |
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