Crown architecture of Larix laricina saplings: shoot preformation and neoformation and their relationships to shoot vigour

1984 ◽  
Vol 62 (11) ◽  
pp. 2181-2192 ◽  
Author(s):  
W. R. Remphrey ◽  
G. R. Powell
Keyword(s):  
Leaf Primordia ◽  
Shoot Length ◽  
Larix Laricina ◽  
Crown Architecture ◽  
Short Shoot ◽  
Shoot Buds ◽  
Lateral Buds ◽  
Lateral Bud ◽  
Long Shoots ◽  
Terminal Buds

Resting buds from five locations on long shoots in each of six crown positions were compared for 30 Larix laricina (Du Roi) K. Koch saplings. At each locus, bud sizes, numbers of bud scales and preformed leaf primordia (basal and axial for long-shoot buds), and apical widths were positively related to parent-shoot length. Along individual shoots, (i) terminal and lateral long-shoot buds contained fewer basal-leaf primordia than the more proximal short-shoot buds; (ii) terminal buds contained the most bud scales and axial-leaf primordia; and (iii) numbers of bud scales increased, while numbers of axial-leaf primordia generally decreased, basipetally among lateral buds. Comparison of bud leaf content with leaves on elongated shoots by regression showed that numbers of preformed and neoformed leaves increased with shoot length, but numbers of neoformed leaves did so to a greater degree. Internode lengths, numbers of leaves per lateral bud produced, and leaf lengths were greater on neoformed than on preformed shoot segments. Because of their capacity for neoformed growth following preformed growth and because of increases in internode lengths among all axial leaves, shoots from subjacent lateral buds replaced experimentally decapitated tree leaders (terminal buds) in one season, with little or no loss of height growth.

Crown architecture of Larix laricina saplings: an analysis of higher order branching

1987 ◽  
Vol 65 (2) ◽  
pp. 268-279 ◽  
Author(s):  
W. R. Remphrey ◽  
G. R. Powell
Keyword(s):  
Simulation Modelling ◽  
Shoot Length ◽  
Larix Laricina ◽  
Structural Development ◽  
Short Shoot ◽  
Lateral Buds ◽  
Architectural Patterns ◽  
Long Shoots ◽  
Short Shoots ◽  
Terminal Shoot

Quantitative analysis and simulation modelling of Larix laricina (Du Roi) K. Koch branches revealed a complex system of architectural patterns and correlations. Numbers of lateral buds and long shoots were positively correlated with parent-shoot length, but the relationships varied among shoot orders and for sylleptic shoots. For order 2 and sylleptic shoots, numbers of lateral long shoots were also correlated with associated terminal-shoot lengths. Sylleptic shoots produced more lateral long shoots than equivalent proleptic shoots. Lateral long-shoot lengths decreased basipetally and were correlated with terminal-shoot lengths. Lengths of order 2 lateral long shoots also varied independently with crown position. Generally, the degree of apical control decreased and the proportion of short shoots increased with positions of less vigour in the crown. Terminal long-shoot lengths varied with parent-shoot length, location, and to some extent parent-axis leader length. Terminal short-shoot production was associated with shorter parent shoots. Shorter order 2 shoots (<60 mm) and most order 3 shoots produced no lateral long shoots. The net result was that branch structural development ceased in less vigorous crown positions. The spatial disposition of shoots, as defined by elevation and divergence angles, varied with position of origin around and along parent shoots. Although variable, elevation angles decreased and divergence angles increased basipetally.

On buds man

2008 ◽  
Vol 84 (4) ◽  
pp. 590-594
Author(s):  
Graham R Powell
Keyword(s):  
Key Words ◽  
Species Identification ◽  
Leaf Primordia ◽  
Adventitious Buds ◽  
Short Shoot ◽  
Shoot Buds ◽  
Tree Crowns ◽  
Vegetative Buds ◽  
Lateral Buds ◽  
Terminal Buds

The nature of scaly buds, homologies of their bud scales and degrees of preformation of contained leaf primordia are briefly described. Distinction is made among vegetative, reproductive, mixed, latent, and adventitious buds. Character of buds as associated with position along and around their supporting shoots and with relative vigour of those supporting shoots is discussed. Reference is made to how knowledge of buds and their fates is useful not only in species identification but also in understanding and modelling development of tree crowns, and in how inter- and intra-generic differences must be accounted for when devising measures to affect development in tree crowns. Key words: bud-scale homology, conifers, hardwoods, lateral buds, leaf primordia, long-shoot versus short-shoot buds, position on shoots, pseudoterminal buds, reproductive buds, terminal buds, vegetative buds

Crown architecture of Larix laricina saplings: sylleptic branching on the main stem

1985 ◽  
Vol 63 (7) ◽  
pp. 1296-1302 ◽  
Author(s):  
W. R. Remphrey ◽  
G. R. Powell
Keyword(s):  
Growth Increment ◽  
Height Growth ◽  
Shoot Length ◽  
Larix Laricina ◽  
Crown Architecture ◽  
Branching Patterns ◽  
Architectural Model ◽  
Long Shoots ◽  
Lateral Branches ◽  
Architectural Characteristics

Sylleptic branching occurred on the current (1983) height-growth increment in 44% of Larix laricina (Du Roi) K. Koch (tamarack) saplings sampled from a natural population near Fredericton, N.B. Although variable, the occurrence and amount of syllepsis tended to increase with parental shoot length. Sylleptic shoots were generally located on the proximal halves of parental shoots. In most cases, the proximally and distally situated sylleptic shoots were somewhat shorter than those in between. The lengths of terminal shoots arising from sylleptic shoots were significantly correlated with parental shoot length, current tree leader length, and location of the branch on its parental shoot. The lengths and elevation angles of terminal extensions from sylleptic shoots tended to be greater than those from nonsylleptic (proleptic) lateral long shoots borne in the same region of the height-growth increment. Architectural characteristics of the extensions resembled those of the more distal proleptic shoots, which develop into major branches. Thus, an additional complement of major lateral branches appeared to be developing where syllepsis occurred. Quantitative relationships depicting sylleptic branching patterns were incorporated into a previous architectural model and simulations of crown architecture which included syllepsis were obtained.

Occurrence and distribution of cones borne laterally on long shoots of Larix laricina

1984 ◽  
Vol 62 (4) ◽  
pp. 771-777 ◽  
Author(s):  
G. R. Powell ◽  
Kathleen J. Tosh ◽  
W. R. Remphrey
Keyword(s):  
Larix Laricina ◽  
Short Shoot ◽  
Shoot Buds ◽  
First Order ◽  
Long Shoots ◽  
Short Shoots

Trees of Larix laricina (Du Roi) K. Koch reaching the stage of first cone bearing tended to produce the majority of their seed cones, and many of their pollen cones, in lateral (axillary) positions along long shoots. In subsequent cone bearing, a greater proportion of the cones occurred in the typical (for the genus) position terminating short shoots. Some trees 2 to 4 m tall bore over 500 lateral seed cones. Lateral cones occurred on all kinds of long shoots, except sylleptic first-order shoots, produced in the 3-year-old portion of the crown. Lateral seed cones were borne on the morphogenically proximal halves of the long shoots and on all surfaces around the circumference of the shoots, but they were less frequent on upper surfaces than on other surfaces. Lateral pollen cones occurred in the proximal 10% of the lengths of the bearing shoots and were restricted to the undersurfaces or sides of the shoots. Lateral cone buds were distinctively larger and contained more bud scales than adjacent lateral short-shoot buds.

Shoot ontogeny in Arctostaphylos uva-ursi (bearberry): the annual cycle of apical activity

1984 ◽  
Vol 62 (9) ◽  
pp. 1925-1932 ◽  
Author(s):  
W. R. Remphrey ◽  
T. A. Steeves
Keyword(s):  
Leaf Primordia ◽  
Growth Strategy ◽  
Bud Burst ◽  
Foliage Leaf ◽  
Lateral Buds ◽  
Previous Season ◽  
Lateral Shoots ◽  
Terminal Buds ◽  
Floral Bracts ◽  
Vegetative Bud

Phenological investigation of shoot ontogeny in the prostrate shrub Arctostaphylos uva-ursi (L.) Spreng. (bearberry) at two sites in Saskatchewan, Canada, revealed that most growth occurred from May to July. Vegetative bud swell and leaf primordium initiation began around the 1st of May. Following bud burst in late May, elongation of most shoots continued for 3 to 5 weeks. Most bearberry shoots were not completely preformed; that is, several neoformed foliage leaves were initiated during current-year shoot extension in addition to the leaves that had been preformed during the previous season and had overwintered in the bud. In many shoots, a terminal inflorescence was initiated in the latter part of May of the year prior to anthesis. During conversion to the flowering state, the terminal apex initiated seven to nine floral bracts, each subtending a bud. In vegetative terminal shoots, bud-scale initiation also began in mid-May to late May and new terminal buds were first evident in early to mid-June. Following the initiation of bud scales and transitional leaves, the production of preformed foliage-leaf primordia continued until about August 1. Protruding lateral buds were evident histologically in the axils of preformed leaves during the initial stages of bud swell. On long, dominant shoots numerous neoformed leaves were initiated and shoot extension was often prolonged well into August. Second-flush terminal and lateral shoots, which resulted from the expansion of neoformed leaves and internodes, were also observed. The occurrence of neoformed growth in a large proportion of shoots suggests an exploitive, opportunistic growth strategy in this species.

The determinate and indeterminate dwarf shoots of Pinus longaeva (bristlecone pine)

1983 ◽  
Vol 61 (9) ◽  
pp. 2280-2290 ◽  
Author(s):  
Frank W. Ewers
Keyword(s):  
Shoot Apex ◽  
Short Shoot ◽  
Age Class ◽  
Pinus Longaeva ◽  
Bristlecone Pine ◽  
Long Shoots ◽  
Significant Change ◽  
Terminal Buds ◽  
Experimentally Induced

The dwarf shoot of the genus Pinus is normally regarded as a determinate short shoot, but the fate of the dwarf shoot apex after needle maturity and the origin of proliferated dwarf shoots remain controversial. To resolve these issues, 1- to 28-year-old dwarf shoots of P. longaeva were microscopically examined and experimentally manipulated. Eighty-eight percent of the lateral long shoots and all trunks had "proliferated dwarf shoots," or dwarf shoots that had become long shoots. On trunks 44.3% of the dwarf shoots had terminal buds, versus 6.6% on lateral long shoots. Most of these buds were microscopic, "interfoliar buds," derived from the original dwarf shoot apex. With advancing age of dwarf shoots there was no statistically significant change in the percentage of dwarf shoots with buds. The fate of the dwarf shoot apex depends upon the position of the dwarf shoot within its age-class and the type of long shoot. On lateral long shoots, only distal dwarf shoots have interfoliar buds and only these may spontaneously proliferate or be experimentally induced to proliferate into long shoots. Proximal dwarf shoots have a suberized apex. On trunks, both distal and proximal dwarf shoots often have buds and can thus proliferate. Dwarf shoot proliferations therefore arise predictably from interfoliar buds and not adventitiously.

Syllepsis in Larixlaricina: analysis of tree leaders with and without sylleptic long shoots

1987 ◽  
Vol 17 (6) ◽  
pp. 490-498 ◽  
Author(s):  
G. R. Powell
Keyword(s):  
Developmental Pathways ◽  
Lateral Buds ◽  
Long Shoots ◽  
Short Shoots ◽  
Terminal Buds ◽  
Lateral Axis

Nonsylleptic and lightly, moderately, and heavily sylleptic leaders with 0 and 1–8, 9–17, and 18–38 sylleptic long shoots, respectively, were cut from 8-year-old Larixlaricina (Du Roi) K. Koch trees. The leaders showed considerable crookedness but degrees of crookedness were not significantly different among leader classes. Leaders of all classes bore sylleptic short shoots. These sylleptic short shoots were largest at midleader locations and larger on leaders with sylleptic long shoots than on nonsylleptic leaders. The terminal buds on many sylleptic short shoots were of long-shoot type. Some sylleptic short shoots with such buds occurred in mid- and proximal-leader positions, whereas lateral buds of the long-shoot type occurred only in distal-leader positions. Sylleptic long and short shoots greatly increased the numbers of leaves on the leaders. This leaf increase occurred principally on the proximal halves of the leaders where leader diameters also increased. Larger amounts of xylem accounted for most of the diameter increases. Subtending leaf to lateral axis distances increased acropetally among lateral buds and sylleptic shoots, but for the latter, these distances were greatest in the middle parts of the respective zones of occurrence. The large variety of developmental pathways for lateral axes on leaders was discussed.

Shoot-length frequencies in black birch (Betula lenta)

1991 ◽  
Vol 21 (10) ◽  
pp. 1475-1480 ◽  
Author(s):  
Brayton F. Wilson
Keyword(s):  
Main Axis ◽  
Shoot Length ◽  
Short Shoot ◽  
Lateral Shoot ◽  
Shoot Production ◽  
Shoot Number ◽  
Individual Branch ◽  
Axis Elongation ◽  
Long Shoots ◽  
Short Shoots

Lengths of all parent and current shoots were measured on three 8- to 10-year-old black birch (Betulalenta L.) trees with branches <8 years old. Older branches had more short shoots (<1 cm long) and shorter long shoots (>2 cm long) than younger branches. Parent long shoots produced three to nine basal short shoots. Observations on short-shoot production were consistent with the hypothesis that only buds with adequate nutrition formed long shoots. Three growth rules were developed for a model that simulated individual branch growth: (i) a regression predicting lateral shoot number from each parent shoot length; (ii) probabilities for the number of short shoots produced by a parent shoot based on the total number of current shoots produced per parent shoot; (iii) a regression predicting current shoot length from parent shoot length, current shoot position (longest to shortest), branch age, and main-axis elongation in the current and previous year. Simulations of 81 branches using these rules predicted shoot numbers and total shoot lengths close to those of the actual branches (R2 = 0.73–0.84).

Compensatory shoot growth in young black birch and red maple trees

1993 ◽  
Vol 23 (2) ◽  
pp. 302-306 ◽  
Author(s):  
Brayton F. Wilson
Keyword(s):  
Compensatory Growth ◽  
Shoot Growth ◽  
Shoot Length ◽  
Red Maple ◽  
Single Treatment ◽  
Frequency Distributions ◽  
Lateral Buds ◽  
Long Shoots ◽  
Short Shoots ◽  
Whole Tree

Black birch (Betulalenta L.) and red maple (Acerrubrum L.) trees 1.5–2 m tall responded by compensatory (increased) shoot growth following a single treatment where shoots on the whole tree were clipped. Total shoot length of clipped trees recovered to control levels after 1 year's growth. The remaining buds on clipped shoots grew more than they would have without clipping. Frequency distributions of shoot lengths shifted toward longer lengths in clipped trees in the 1st year, but were similar to controls 2 years after clipping. The longest shoots were as long, or longer, on clipped shoots as on unclipped shoots. The major compensatory growth mechanism was increased growth of lateral buds. Clipping induced a few preventi-tious buds to form shoots and a few unclipped short shoots to grow as long shoots.

Crown architecture of Larix laricina saplings: quantitative analysis and modelling of (nonsylleptic) order 1 branching in relation to development of the main stem

1984 ◽  
Vol 62 (9) ◽  
pp. 1904-1915 ◽  
Author(s):  
W. R. Remphrey ◽  
G. R. Powell
Keyword(s):  
Morphological Variability ◽  
Natural Populations ◽  
Height Growth ◽  
Main Stem ◽  
Larix Laricina ◽  
Crown Architecture ◽  
Growth Increments ◽  
Long Shoots ◽  
Architectural Models ◽  
Short Shoots

The upper 5 years of crown growth in samples of Larix laricina (Du Roi) K. Koch (tamarack) saplings from natural populations in the Fredericton, N.B., area provided data to model architectural relationships describing patterns of (nonsylleptic) order 1 branching in relation to development of the main stem. The model was based on relationships between branch extension and height growth, and numbers and positions of order 1 branches. Elevation angles of shoots making up the branches, and conversion of order 1 long shoots to order 1 short shoots were also incorporated. Lengths of current shoots of major order 1 branches tended to decrease with increasing depth in the crown. Similar tendencies occurred among lengths of all current branch extensions within single height-growth increments, but the decreases in length became less regular with increasing age of branch. Because the relationships were complex, alternative approaches to modelling shoot lengths were adopted to enhance understanding of the patterns involved. Deterministic and stochastic elements were used in the overall model to account for significant proportions of morphological variability. Simulations based on the alternatives within the model were realistic in their interpretations of actual sapling crown architecture. Classification of L. laricina according to previously proposed architectural models that qualitatively describe general development was discussed.

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