• Journal of Plant Biology
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• v.36 no.1
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• pp.35-42
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• 1993

This study deals with the effect of dwarf growth for the wood and the structural changes of cambium in Pinus koraiensis subjected to water stress. The length and wall thickness of tracheary elements in dwarf trees was shorter and thicker than that in normal trees. The redial width and cell number of the annual rings are narrower and smaller in dwarf trees than those in normal trees. In serial tangential sections, the frequency of anticlinal division is low and loss of cambial initials is small in dwarf trees. The length of cambial initials in water deficit, trees are slightly shorter than that in normal trees, and the instructive growth of cambial initials during differentiation of xylem mother cells is inactive in dwarf trees. Thus, it is interpreted that the shortening of tracheary elements in dwarf trees is due to the fact that the length of cambial initials are shortened and the intrusive growth of those during differentiation of xylem mother cells is inactive. The structural variations in the wood of naturally occurring dwarf trees are similar to those of trees subjected to artificial water stress. Therefore, it is suggested that the variation of xylem element in dwarf trees are related to water conditions.

• Journal of Plant Biology
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• v.36 no.3
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• pp.251-257
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• 1993

The size variation of the cambial initials and their derivatives, in relation to the increase of girth, in the intact and decapitated stem of Populus euramericana was anatomically studied. In the typical nonstoried cambium of P. euramericana, the cell size of fusiform initials, vessel member, and sieve tube member were gradually increased and thus it reached a maximal state. In the intact plants, the size of the cambial initials and their derivatives was larger then in the decapitated ones. On the other hand, the frequency of anticlinal division of the cambial cells, the rate of the elongation and loss of the daughter initials in the intact plants was higher than in the decapitated ones. The cambium of the intact plants had higher ray compared with that of the decapitated ones. It was interpreted that these results were caused by the decapitation, which could block the supply of certain substances for cell growth such as hormones and metabolites.

• Journal of Plant Biology
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• v.36 no.1
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• pp.29-34
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• 1993

Observation was made on early ontogeny of vascular cambium in the cotyledonary node of Pinus koraiensis seedling in order to clarify the cambial ontogeny of the node which was hardly elongated. In transverse view, the derivatives by the early periclinal divisions at the outer region of the procambial strands differentiated to protophloem with establishing a certain degree of radial seriations. Later, some cells in the central region of the procambial strands begin divide periclinally, eventually the cells, differentiate gradually to the vascular cambium. In tangential view, early procambium is consisted of homogeneous short cells with transverse end walls which are tansformed into the long cells and short cells gradually. The long cells continue intrusive growth and the short cells repeat transverse division. Finally, the long and short cells differentiated to cambial fusiform initials and ray initials respectively. In tangential section, the differentiation pattern of cambial initials resembles that of the stem of Ginkgo biloba. But in transverse view, the characteristics in the origin of vascular cambium of the cotyledonary node resembles that of root. The vascular cambium in cotyledonary node is completed after eleven prophylls were formed.

• Journal of Plant Biology
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• v.34 no.3
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• pp.191-199
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• 1991

This study has been conducted to investigate the developmental changes of cambial initials and their derivatives in relation to the growing girth of tree in Diosypros kaki and Firmiana simplex. In D. Kaki and F. simplex with typical storeyed cambium, increase in the girth of camium occurred by radial anticlinal division in general, however occasionally the increase was companied by pseudotransverse division. The length of fusiform initials, vessel member, and sieve tube member remained relatively constant throughout the secondary growth but that of fiber showed general tendancy to increase with growing girth of tree. During the girth increase of tree, height and number of ray remained constant in D. kaki, however in F. simplex, height of ray markedly decreased while the number of ray per unit area more or less increased. The secondary ray was originated from the segmentation or division of the side or end of fusiform initials.

• Journal of Plant Biology
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• v.36 no.3
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• pp.275-279
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• 1993

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.

• Korean Journal of Plant Resources
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• v.11 no.3
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• pp.326-334
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• 1998

Vascular cambium in 16 species of Salicaceae is nonstoried in all of them and is made up of fusiform and ray initials. The growth of cambial girth occurred by pseudotransverse division of fusiform initials and subsequent apical intrusive growth of daughter initials. The measurements of fusiform initials in tangerntial sections have revealed that the average length varies from 252.2-437.1${\mu}{\textrm}{m}$ in investigated species, with the maximum being in Populus euramericana and the minimum in Salix purprea var. Multinervis. The length of fusiform initials depends on the length of the tapering end wall , therefore, the longer the length of the tapering end wall, therefore, the longer the length of the taperding end wall, the longer the length of fusiform initials. Ray initials have their own size, magnitude, and frequency of occrrence in each species. The relative proportion of ray initials fall about 15.0-24.5% in Salicaceae. Shrubby species of Salix have a lower ratio of ray initials than the species which possess wider trunks. New ray initials are originated from cut off the side or the end of fusiform initials and central partition of a fusiform initials.

• Journal of Plant Biology
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• v.33 no.1
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• pp.65-72
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• 1990

An anatomical study was conducted in order to elucidate the development of primary and secondary ray in Robinia pseudoacacia L. The height of primary ray near pith decreases progressively toward periphery, while the width and number per unit area gradually increase, and then the height, width and number remain somewhat constant. Secondary ray originates from the segmentation of fusiform initials or division of the side or end of fusiform initials at the middle of the first growth layer. And after the height and width of secondary ray increases to some extent, it remains constantly.

• Journal of Plant Biology
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• v.32 no.4
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• pp.305-312
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• 1989

Developmental anatomy was conducted in order to elucidate the differentiating pattern of fascicular cambial initials in the hypocotyl of Ricinus communis. The homogeneous procambium with relatively short cells in early stage is transformed into a heterogeneous structure with long and short cells in late stage in tangential view. Fusiform and ray initials are gradually originated from the long and short cells of the procambium in hypocotyl in later stage respectively. Fusiform initials are not shorter than procambial cells because of the successive elongation of vascular meristematic cells. Therefore, the distinction between procambium and fascicular cambium is not made from comparison with their cell length. The characteristics of the fascicular cambium are gradully acquired at or just after completion of hypocotyl elongation.

• Journal of Plant Biology
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• v.34 no.4
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• pp.311-316
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• 1991

The origin of cambial initials from procambium was studied in the seedling root of Acer saccharinum. In transverse view, the first periclinal divisions of procambial cells occurred just outside of each early metaxylem and resulted in meristematic strips. As root development progressed, the division activities appeared subsequently outside of each late metaxylem and then in pericycle cells opposite the four protoxylem poles. Eventually, such meristematic strips were connected completely each other. Thus, a nearly rectangular shaped meristematic layer in outline was formed outside the xylem in a whole root transectioned. In tangential section, early procambium showed a homogeneous structure consisted of uniform short cells with transverse end walls. However, some of the procambial cells did elongate, whereas others divided transversely. The former become more elongate, tapered, and vacuolated. Finally, they differentiated into fusiform initials. Short cells consisting axial strands divided continuousely in transverse plane and became ray initials, while some short cells elongated and transformed into long cells. The early ontogeny of vascular cambium in Acer saccharinum root was interpreted to be established by a gradual process.

• Journal of Plant Biology
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• v.37 no.3
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• pp.317-323
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• 1994

The calluses formed on the surface of a quarter-girdled Robinia pseudoacacia stems have been shown to originate from immature xylem cells and preexisting cambial cells. The cellus is not only formed by periclinal and anticlinal divisions of radial cells, but also axial cells. In tangential view, the callus at initial stage showed heterogeneous structure composed of long and short cells and then homogeneous one with short cells. Some cells of homogeneous structure in middle region of callus at early stage is later elongated and others mainly divided in trasverse plane. In the result the homogeneous structure becomes into a heterogeneous one. Subsequently, the long cells in heterogeneous structures elongated further and became fusifrom initials, and the short cells divided transversely became ray initials. The appearence of homogeneous and heterogeneous structure in the callus on debarked stem without organ elongation is almost similar to that of the structure in the procambium of young stem which is elongating extensively. Eventually, the ontogeny of vascular cambium in wound callus resembles that of a young stem grown normally, although the debarked stem does not grow in length but in girth and the young stem elongates activity. These findings mean that the active intrusive growth of short procambial cells occurs during the differentiation of fusiform cambial cells.