Frequency Of Anticlinal Division Research Articles

Interrelationship between mean length, rate of intrusive elongation, frequency of anticlinal divisions and survival of fusiform initials in cambium

Interrelationship between mean length, rate of intrusive elongation, frequency of anticlinal divisions and survival of fusiform initials in cambium

The formation of heterogeneous storeys in the cambium on the example of Laburnum anagyroides Medik

The formation of the storeyed pattern of cambium in the first two years of cambial activity and the structure of mature cambium was examined in <i>Laburnum anagyroides</i>, a decorative shrub growing in temperate climate. A distinct storeyed pattern was observed in two-year-old stems, despite the presence of tall rays. The heterogeneous nature of storeys was revealed by the analysis of i) the number of fusiform initials forming storeys or groups of packets; and ii) the frequency of anticlinal divisions in the examined years of cambial activity and the calculation of the relative increase of the cambial circumference. The results are discussed on the basis of the recent hypothesis of intrusive growth of fusiform initial, occurring between the tangential walls of its neighbouring initial and its closest derivative.

Development of cambium and length of vessel elements and fibers in dwarfAlnus hirsuta (Spach) rupr

In a comparison of cambial cells and their derivatives between naturally occurring dwarf and normal trees, vessel elements and fibers in the annual rings of dwarf trees were found to be shorter, narrower and fewer than those of normal trees. The frequency of anticlinal divisions and loss of cambial initials were low during the differentiation of xylem cells from cambial initials in dwarf trees. The length and intrusive growth of fusiform initials were slightly less than those of normal trees. Thus, it was concluded that the shortening of vessel elements and fibers in dwarf trees was due to the fact that cambial initials were themselves shortened and underwent inactive intrusive growth during differentiation of the xylem mother cells.

Cambial Development and Tracheid Length of Dwarf Pines (Pinus Densiflora and P. Thunbergii)

From a comparison of cambial cells and their derivatives between naturally occurring dwarf trees and normal ones, it was concluded that tracheids in the annual rings of dwarf trees are shorter, narrower and fewer than those of normal trees. The frequency of anticlinal division and loss of cambial initials is low during differentiation of xylem cells from cambial initials in dwarf pines. The length and intrusive growth of fusiform initials are slightly less than those of normal trees. Thus, it is concluded that the shortening of tracheids in dwarf trees is due to the fact that cambial initials are themselves shortened and that intrusive growth during differentiation of xylem mother cells has occurred.

Control of fusiform initial orientation in the vascular cambium of Abies balsamea stems by indol-3-ylacetic acid

Fusiform initial reorientation, deduced from changes in tracheid arrangement, was investigated in helical bridges left after Abies balsamea stems were girdled. The first responses included an increase in the number of S- and Z-oriented anticlinal divisions without any change in their ratio, a decrease in fusiform initial length, and the formation of traumatic resin canals. Subsequently, normal tracheid differentiation resumed, the frequency of anticlinal divisions further increased, and there was an increase in the number of oriented intrusive growth events. The orientations of the anticlinal wall and of the intrusive growth were predominantly in the direction that eventually would result in the fusiform initials being aligned parallel to the bridge angle. The application of exogenous indol-3-ylacetic acid to the upper edge of a helical bridge inhibited fusiform initial reorientation, mainly by decreasing the frequency of oriented intrusive growth events. However, immediately below the application point, exogenous indol-3-ylacetic acid also induced the fusiform initials to begin temporarily to realign so as to be perpendicular to the bridge angle. The transport of a pulse of [1-14C]indol-3-ylacetic acid applied to the shoot apex was inhibited 1 day after girdling in both helical and longitudinal bridges, particularly the former, whereas it was inhibited only in helical bridges at the end of a subsequent 11-week growing period. The degree of inhibition in the helical bridges was greater the day after girdling than at the end of the growing period, during which interval fusiform initial reorientation occurred at the bottom of the bridge width. The results support the conclusion that the orientation of fusiform initials is parallel to the direction of indol-3-ylacetic acid transport.

Variations in cell length and frequency of anticlinal division in the vascular cambium throughout a white spruce tree

In the early growth of the stem, branches, and roots, the vascular elements are relatively short and the frequency of anticlinal division involved in cambial cell multiplication is high. As growth sheaths are added in the stem, length of cell increases and rate of multiplicative division declines. A similar trend occurs upward through the lower quarter to half the height of the stem. In the root system, the later growth of vertical roots is characterized by shortness of cell and high frequency of anticlinal division, and conversely, that of horizontal roots by great length of cell and low rate of anticlinal division. Although a general negative relationship exists between rate of anticlinal division and cell length throughout much of the tree, these features sometimes vary independently, and length of cell seems to be more closely related to amount of yearly radial accretion. Through the middle to late growth of the stem a negative relationship obtains between length of cell and width of annual ring, cell length maximating at a ring width of 1–2 mm. At this stage, frequency of division may fluctuate only narrowly over a considerable range of ring width. A continued decline in ring width to less than 0.5 mm, such as may occur on senescence, is accompanied by decreased cell length and accelerated anticlinal division. Length of the cell plate in anticlinal division, relative to that of the dividing cell, is greater in the early growth of the stem and branches and throughout horizontal roots than elsewhere in the tree. Most of the anticlinal divisions are pseudotransverse. The proportion of lateral divisions ranges from about 1% in the late growth of stems to 11% in horizontal roots.

Developmental Changes in the Vascular Cambium of Polygonum lapathifolium

Developmental changes in the vascular cambium of Polygonum lapathifolium were determined primarily by an analysis of the secondary xylem. The cambium and xylem consist of fascicular and interfascicular regions in this herbaceous dicotyledon. Near the pith vessels are restricted to the fascicular regions of the xylem. During secondary growth vessels are formed in some radial files in the interfascicular regions. Anticlinal divisions are of two types, oblique and lateral. In interfascicular files consisting of fibers only, about two-thirds of the anticlinal divisions are oblique. The oblique partition averages 31% of the length of the dividing initials. In interfascicular files consisting of vessel elements and fibers, there are almost equal numbers of oblique and lateral divisions. The oblique partition averages 37% of the length of the dividing initials in these files. Lateral divisions account for approximately three-fifths of the anticlinal divisions in the fascicular regions, consisting of vessel elements and fibers. The partitions formed in oblique anticlinal divisions average 64% of the length of the dividing cells in the fascicular regions. The frequency of anticlinal division is much higher in files consisting of vessel elements and fibers than in those consisting of fibers only. There is no loss of fusiform initials, except by ray formation. Ray initiation occurs by simple subdivision of fusiform initials. The findings are discussed in relation to the developmental changes in the vascular cambium in plants of different habits.

DEVELOPMENTAL CHANGES IN THE VASCULAR CAMBIUM OF POLYGONUM LAPATHIFOLIUM

Developmental changes in the vascular cambium of Polygonum lapathifolium were determined primarily by an analysis of the secondary xylem. The cambium and xylem consist of fascicular and interfascicular regions in this herbaceous dicotyledon. Near the pith vessels are restricted to the fascicular regions of the xylem. During secondary growth vessels are formed in some radial files in the interfascicular regions. Anticlinal divisions are of two types, oblique and lateral. In interfascicular files consisting of fibers only, about two‐thirds of the anticlinal divisions are oblique. The oblique partition averages 31% of the length of the dividing initials. In interfascicular files consisting of vessel elements and fibers, there are almost equal numbers of oblique and lateral divisions. The oblique partition averages 37% of the length of the dividing initials in these files. Lateral divisions account for approximately three‐fifths of the anticlinal divisions in the fascicular regions, consisting of vessel elements and fibers. The partitions formed in oblique anticlinal divisions average 64% of the length of the dividing cells in the fascicular regions. The frequency of anticlinal division is much higher in files consisting of vessel elements and fibers than in those consisting of fibers only. There is no loss of fusiform initials, except by ray formation. Ray initiation occurs by simple subdivision of fusiform initials. The findings are discussed in relation to the developmental changes in the vascular cambium in plants of different habits.

CELL LENGTH AND RATE OF ANTICLINAL DIVISION IN THE CAMBIUM OF THE SEQUOIAS

This report deals with the frequency of anticlinal (multiplicative) divisions in fusiform cambial cells, cell length at the time of division, and ring width as determined mostly in Sequoia sempervirens. The general relationships between these anatomical features resembled those observed in other conifers, but the frequency of anticlinal division was relatively high and the cells were long. Accordingly, the rate of cambial cell lengthening in the repetitive cycle of anticlinal division and cell elongation was found to exceed that in other conifers. Upward in the lower part of the stem the rate of anticlinal division decreased and cell length increased. A comparatively high rate of anticlinal division was maintained in the peripheral growth of large boles in both species, but cell length was greater in S. sempervirens than in S. gigantea.

THE RATE OF ELONGATION OF FUSIFORM INITIALS IN THE CAMBIUM OF PINACEAE

This report deals with the rate and amount of elongation of fusiform initials in the cycle of cell elongation and multiplication by pseudotransverse division which accompanies circumferential expansion of the cambium. In the recent growth of mature trees the yearly amount of cambial cell elongation drops as ring width decreases, but not in proportion to the decline in ring width. The cumulative elongation through lineal series of cells, per centimeter of xylem increment, increases as ring width decreases. The amount of cell elongation during the production of several narrow rings greatly exceeds that through a single wide ring having the same total width. It seems clear that the time factor is important in the elongation of cambial cells, and to some extent the interrelated frequency of anticlinal division, particularly when radial growth declines.

TRACHEID SIZE AND ANTICLINAL DIVISIONS IN THE CAMBIUM OF PSEUDOTSUGA

This study is concerned with certain aspects of cambial behavior and tracheid size in Douglas-fir. Geographical origin of material was Colorado, Utah, Wyoming, Washington, and several localities in British Columbia from Golden to Vancouver Island. Tracheids were smallest in all dimensions in the Colorado collections and largest in wood from coastal British Columbia. In second growth trees 35–70 years old and 10–20 in. in diameter maximum cell length was associated with a ring width of approximately 1 mm, the length declining in both wider and narrower rings. Increase in girth was accompanied by pseudotransverse divisions, these occurring mostly in fusiform cells functioning as initials, and only rarely in derived xylem mother cells. At breast height the frequency of pseudotransverse division centered about a rate of 1.3 divisions per centimeter of xylem increment when rings were 2–7 mm wide. Reduction in ring width below 1 mm occasioned a rise in frequency of anticlinal division with consequent cell shortening. In the recent growth of old trees 475–675 years old and 3–7 ft in diameter similar relationships prevailed between frequency of anticlinal division, cell length, and ring width, but mean values for rate of division and cell length differed slightly from those for young trees. Upward in the bole, to a height of 50 ft, anticlinal divisions decreased in frequency and cell length increased, but the amount of cell lengthening was greater than could be accounted for by the change in rate of division. Notable differences in rate of division occurred between neighboring trees on most sites. Although pseudotransverse divisions took place at various times during the growing season, most were aestival. Length of the partition in pseudotransverse division, although fluctuating from cell to cell, was, in general, directly related to length of the cambial cell undergoing division. The orientation of the partition in anticlinal division was usually unidirectional in neighboring cells, but occasionally an indeterminate condition prevailed. When unidirectional, reversals in direction of tilt occurred after varied intervals. Duration of the latter tended to be inversely related to the frequency of pseudotransverse division.

CAMBIAL BEHAVIOR WITH REFERENCE TO CELL LENGTH AND RING WIDTH IN PINUS STROBUS L.

The relationships between width of annual rings, length of wood cells, and frequency of anticlinal (multiplicative) divisions in fusiform cambial cells were studied by reference to trees of various growth patterns. The trees selected ranged from 8 to 20 in. diameter and included both open-grown specimens with branches close to the ground and forest types with tall, slender shafts. Much fluctuation was noted among individual trees, but in general there was, in the peripheral growth, an inverse relationship between length of wood cells and width of annual rings. The frequency of anticlinal divisions in the cambium remained at a more or less uniform rate in trees with rings from 1.5 to 5 mm wide, but rose sharply when ring width fell below 1.3 mm. This was in contrast to the situation observed earlier in Thuja occidentalis where the rise in frequency of anticlinal divisions was slight and occurred only in trees with rings less than 0.3 mm wide.

CELL SIZE AND SURVIVAL IN CONIFER CAMBIUM

The pseudotransverse divisions of fusiform initials by which the cambium of conifers is accommodated to increasing girth tend to occur at relatively high rates of frequency. The overproduction of new initials is accompanied by extensive cell loss. The continuation or reduction of fusiform initials after origin in anticlinal division is evidently related to cell length and extent of ray contacts. The largest fusiform initials generally survive and repeat the cycle of elongation and multiplication by pseudotransverse division. The cells of intermediate length continue or fail in varying proportions, the rate of failure tending to rise with increasing frequency of anticlinal division. As a rule the initials with the largest area of ray contacts persist and those with sparse ray contacts decline. The shortest fusiform initials are usually lost, passing off into maturation or undergoing further diminution to ray initials. The continued selection of the longest of the newly formed fusiform initials, which is operative at all stages in tree growth, undoubtedly contributes to the maintenance of an efficient cell length in the secondary vascular tissues.

The Frequency of Anticlinal Divisions in Fusiform Cambial Cells of Chamaecyparis

The Frequency of Anticlinal Divisions in Fusiform Cambial Cells of Chamaecyparis