Within-crown distribution of male and female cones on clonal Sitka spruce trees

The within-crown distribution of cones (strobili) was mapped on 48 mature grafts of Sitka spruce [Picea schensis (Bong.) Carr.]. The total number of cones per tree was increased by a mainstem injection of 20 mg GA_4/7 and 8 mm wide bark ring. The cones and buds were classified as either lateral or terminal on each individual branch. The distribution of lateral female, terminal female, lateral male and terminal male cones, showed a general progression from the upper distal to lower proximal regions of the tree crown in all 12 clones. Evidence for preferential allocation of cones to particular branch types is presented. The region of the tree with the greates number of cones varied with treatment and reflected differences in the sex ratio of the individual trees. There is evidence for a relationship between branch length, position within the crown and the type of cone produced.     

SYMMETRY AND DEVELOPMENT OF LIMNOBIUM SPONGIA (HYDROCHARITACEAE)

Limnobium spongia produces upright vegetative axes and prostrate stolons. The upright axes bear new stolons, whereas the stolons bear new upright axes and fertile and sterile branching systems. Upright axes and fertile and sterile branching systems are all interpreted to have sympodial growth. However, it was not determined whether growth of stolons is monopodial or sympodial. Both stolons and upright axes branch in alternate plastochrons, and branching is achieved solely by the bifurcation of apical meristems. Each meristematic bifurcation is interpreted to represent the formation of a precocious lateral bud. The upright axes develop from presumed precocious lateral buds on stolons, whereas such buds on upright axes produce renewal shoots. Limnobium spongia exhibits a marked degree of mirror-image symmetry.     

Branch architecture,light interception and crown development in saplings of a plagiotropically branching tropical tree,Polyalthia jenkinsii (Annonaceae)

To investigate crown development patterns, branch architecture, branch-level light interception, and leaf and branch dynamics were studied in saplings of a plagiotropically branching tree species, Polyalthia jenkinsii Hk. f. & Thoms. (Annonaceae) in a Malaysian rain forest. Lengths of branches and parts of the branches lacking leaves ('bare' branches) were smaller in upper branches than in lower branches within crowns, whereas lengths of 'leafy' parts and the number of leaves per branch were larger in intermediate than in upper and lower branches. Maximum diffuse light absorption (DLA) of individual leaves was not related to sapling height or branch position within crowns, whereas minimum DLA was lower in tall saplings. Accordingly, branch-level light interception was higher in intermediate than in upper and lower branches. The leaf production rate was higher and leaf loss rate was smaller in upper than in intermediate and lower branches. Moreover, the branch production rate of new first-order branches was larger in the upper crowns. Thus, leaf and branch dynamics do not correspond to branch-level light interception in the different canopy zones. As a result of architectural constraints, branches at different vertical positions experience predictable light microenvironments in plagiotropic species. Accordingly, this pattern of carbon allocation among branches might be particularly important for growth and crown development in plagiotropic species.     

Correlation between trunk and branch age in trees as a new parameter in the analysis of tree architecture

A method for characterizing tree form is developed by linear regression of the age of the trunk on the average branch age at different heights. This relationship holds for a wide variety of situations, including both theoretical models and observed tree samples. The intercept of the regression, a, the ‘index of trunk distinctness’, reflects the branching pattern inherent to the species and indicates whether the trunk is erect or not. The slope, b, is termed the ‘crown thickness coefficient’, because it indicates a branching pattern. Tree forms can be classified into nine theoretical groups; three of these are physically impossible. The method was applied to real trees and a and b are shown to be useful tree form characteristics. Possible applications of the method are briefly discussed.     

辽东栎林内不同小生境下幼树植冠构型分析

以黄土高原黄龙山林区辽东栎林内3个小生境（林下、林隙、林缘）下辽东栎天然更新幼树为研究对象,采用典型抽样法对辽东栎幼树侧枝、叶片和树冠的空间分布状况以及生物量分配状况进行调查分析,探讨微生境与幼树植冠构型特征的关系,明确辽东栎幼树对不同小生境的适应策略,为栎林经营和林分结构优化提供理论依据。结果显示：（1）3种生境下辽东栎幼树构型发生了可塑性变化,林下幼树树冠层次比较单一,林隙与林缘的幼树树冠层次更加丰富。（2）由林下至林缘,幼树的树高、枝下高呈逐渐减小的趋势,而地径变化趋势与之相反;幼树的冠幅、树冠面积、树冠率呈先增加后减小的趋势,并且林下与林隙、林缘的差异显著;幼树的总体分枝率、逐步分枝率、枝径比呈先增加后减小的趋势。（3）3种生境下,幼树的一级枝的枝长、直径与倾角随着树高的增加而呈减小的趋势,但3种生境的差异不显著;林下一级枝主要分布在冠层中上部,而林隙与林缘一级枝主要分布在冠层中下、中上部。（4）由林下至林缘幼树叶长、叶宽、单叶面积和比叶面积逐渐降低,而单株叶数、叶总面积、叶面积指数呈先增大后减小趋势;与其他2种生境相比林下叶片分布趋于冠层上部。（5）幼树地上部分生物量中林下主干生物量占83%,枝和叶生物量只占17%;而林隙与林缘虽然各部位生物量有所差异但比例基本一致,其中主干占66%左右,枝和叶生物量占34%左右。研究表明,林隙生境下幼树的构型优于林缘和林下生境,在今后栎林的经营中,可以通过适当间伐来增加林隙数量,为森林更新和结构的优化提供有利条件。     

Bud Content and its Relation to Shoot Size and Structure in Nothofagus pumilio(Poepp. et Endl.) Krasser (Nothofagaceae)

Buds of shoots from the trunk, main branches, secondary branchesand short branches of 10–21 year-old Nothofagus pumiliotrees were dissected and their contents recorded. The numberof differentiated nodes in buds was compared with the numberof nodes of sibling shoots developed at equivalent positionsduring the following growing season. Axillary buds generallyhad four cataphylls, irrespective of bud position in the tree,whereas terminal buds had up to two cataphylls. There were morenodes in terminal buds, and the most distal axillary buds, oftrunk shoots than in more proximal buds of trunk shoots, andin all buds of shoots at all other positions. The highest numberof nodes in the embryonic shoot of a bud varied between 15 and20. All shoots had proximal lateral buds containing an embryonicshoot with seven nodes, four with cataphylls and three withgreen leaf primordia. The largest trunk, and main branch, shootswere made up of a preformed portion and a neoformed portion;all other shoots were entirely preformed. In N. pumilio, theacropetally-increasing size of the sibling shoots derived froma particular parent shoot resulted from differences in: (1)the number of differentiated organs in the buds; (2) the probabilityof differentiation of additional organs during sibling shootextension; (3) sibling shoot length; (4) sibling shoot diameter;and (5) the death of the apex and the most distal leaves ofeach sibling shoot. Copyright 2000 Annals of Botany Company Axis differentiation, branching, bud structure, leaf primordia, neoformation, Nothofagus pumilio, preformation, size gradient     

Plastic Response of Crown Architecture to Crowding in Understorey Trees of Two Co-dominating Conifers

Crown architecture and growth rate of trunk height, trunk diameterand lateral branches of understorey trees (5–10m tall)were compared between two co-dominating conifers,Abies sachalinensisandPiceaglehnii, in relation to the index of local crowding intensity,W,represented as a function of density, distance and basal areaof taller neighbours. For the two conifers, the growth of trunkheight and diameter was decreased and crowns became flat withincreasingW, keeping crown projection area. Self-pruning oflower branches was more intense inAbiesthan inPiceain crowdedconditions, while both conifers showed similar crown forms inless crowded conditions. These results suggest that the growthin lateral branches exceeded that in height in crowded conditions,especially inAbies. Tree age of both conifers increased withincreasingW, resulting from the low growth rate in crowded conditions.The age of the longest and lowest branch ofPicea, up to 150years, was positively correlated with the tree age ranging from70 to 250 years, whereas that ofAbieswas constant at around30 years irrespective of tree age varying from 40 to 140 years.This result agrees with the observation that agedAbieshad moreflat-shaped crowns than in agedPiceain crowded conditions. Theseresults suggest that each conifer adapted to crowding in differentways: high elongation of branches with high turnover rate forAbiesandviceversaforPicea. Abies; crown form; neighbourhood interference; Picea; plasticity     

COMPUTER SIMULATION OF BRANCH INTERACTION AND REGULATION BY UNEQUAL FLOW RATES IN BOTANICAL TREES

Two aspects of branch interaction in trees are investigated theoretically. In the first it is assumed that there is a controlling factor in which the proximity of neighboring terminal branch units influences their branching capability. The almost horizontal tiers of lateral branches of Terminalia catappa L. and Cornus alternifolia L. are simulated by computer using values based on the measured branch geometries of real trees. For branch interaction, we assume a horizontal circle of inhibition whose center is the existing terminal point of a branch. If the end point of another branch extends into the circle, the original branch fails to bifurcate. Examples of computer simulated patterns are illustrated using different degrees of interference and are compared with branch tiers in T. catappa. In the second model the ability of a terminal branch unit to bifurcate is considered to be determined by the accumulation of a critical amount of a hypothetical growth- or bifurcation-determining factor. The daughter branches of a bifurcation are assumed to have differing “flow rates,” i.e., the factor is distributed in different amounts between different daughter axes. Some simulated patterns generated by this model are very similar to real patterns found in T. catappa and an unnamed species of Tabernaemontana. In both simulations bifurcation ratios are determined and are shown to be a variable, not a fixed, property of the simulated trees.     

The development of Archaeopteris: new evolutionary characters from the structural analysis of an Early Famennian trunk from southeast Morocco

A 5 m long trunk of a young Archaeopteris/Callixylon erianum tree from the Late Devonian of Morocco shows new branching patterns for early lignophytes. This progymnosperm tree produces a helical pattern of traces that we infer belonged to reduced, short-lived, primary (apical) branches (type A) as well as two types of adventitious traces (types B and H). We infer that type-B traces supplied branches that initiate close to the site of attachment on the trunk of some, but not all type-A branches in an irregular but nonrandom pattern. Unlike ephemeral type-A branches, those of type B persist and become long-lived, potentially permanent units of the architecture of Archaeopteris trees. Type-H adventitious traces are also short-lived and occur singly or in serial groups, but differ from traces of either type A or B branches by lacking differentiation into a readily identifiable organ category. We interpret type-H traces as supplying latent primordia that could develop into either adventitious roots or shoots depending on extrinsic factors. Our new data suggest that Archaeopteris had a wide range of branch primordium amplitude. Type-B branches compare with axillary lateral branch buds of some Early Carboniferous spermatophytes (Calamopitys) and are a major developmental departure from the strictly apical, pseudomonopodial shoot branching of older aneurophyte progymnosperms. Type-H traces suggest that Archaeopteris trees had some potential for formation of adventitious roots or shoots in response to environmental factors, such as partial burial by overbank sedimentation. Collectively, these novel methods of tree branching may partly explain the extraordinary success and worldwide dominance of Archaeopteris forests on fluvially dominated, Late Devonian floodplains.     

Bud and crown architecture of white spruce and black spruce

Needle primordia in buds and branch lengths were assessed in the crown of a plantation-grown white spruce tree. There was a gradation in needle primordia in buds in branches within the crown. The largest number of primordia was in the terminal bud of the leading main stem shoot, with the number in first-order whorl lateral shoot terminal buds decreasing from whorl 1 to whorl 4, below which buds contained a similar small number of primordia (about one-third as many as in the terminal shoot). Previous year's shoot elongation followed a similar pattern (i.e., elongation of whorl branches was greater closer to the top of the tree and elongation in the fourth through ninth whorls was about one-third that of the main stem leader). Higher order branches within whorls had within-branch gradation in shoot elongation and number of needle primordia, with older branches having as few as 16–30 primordia in buds and 3–4 cm elongation for high-order branches on older main stem whorls. There were strong correlations between the number of primordia in branch terminal buds and branch length/diameter and bud length/diameter/volume. In both black spruce and white spruce, there were strong correlations of number of needle primordia in main stem leader terminal buds with number of needle primordia in terminal buds of first and second whorl leaders.     

辽东栎植冠的构型分析

对辽东栎 ( Quercus liaotungensis)个体发育中不同阶段的植冠构型进行统计分析 ,结果发现 :构型转变主要表现在分枝格局上 ,除枝、叶方位角和叶倾角外 ,分枝率、枝长和枝倾角都发生过显著改变。不同阶段构型分析的比较表明 :1 )幼苗阶段 ,高生长显著 ,枝条伸长较快 ,但分枝率低 ;2 )幼树阶段 ,分枝率显著小于成株阶段 ,但上层枝条的平均枝倾角大于其它两阶段 ,上层枝条的长度也大于成株阶段 ;3)成株阶段 ,冠幅迅速扩展 ,分枝率较前两时期显著增加 ,同时顶端优势减弱 ,引起休眠芽萌动和萌生苗的发生。而枝的转向是植物个体发育过程中构型调整的直接证明。这些都说明了辽东栎在生活史的不同阶段 ,因为所处的微生境和所面临的威胁都各不相同 ,在构型表达上也有不同对策。     

SYMMETRY AND DEVELOPMENT OF BUTOMUS UMBELLATUS (BUTOMACEAE) AND LIMNOCHARIS FLAVA (LIMNOCHARITACEAE)

The prostrate rhizome of Butomus umbellatus produces branch primordia of two sorts, inflorescence primordia and nonprecocious vegetative lateral buds. The inflorescence primordia form precociously by the bifurcation of the apical meristem of the rhizome, whereas the non-precocious vegetative buds are formed away from the apical meristem. The rhizome normally produces a branch in the axial of each foliage leaf. However, it is unclear whether the rhizome is a monopodial or a sympodial structure. Lateral buds are produced on the inflorescence of B. umbellatus either by the bifurcation or trifurcation of apical meristems. The inflorescence consists of monochasial units as well as units of greater complexity, and certain of the flower buds lack subtending bracts. The upright vegetative axis of Limnocharis flava has sympodial growth and produces evicted branch primordia solely by meristematic bifurcation. Only certain leaves of the axis are associated with evicted branch primordia and each such primordium gives rise to an inflorescence. The flowers of L. flava are borne in a cincinnus and, although the inflorescence is simpler than that of Butomus umbellatus, the two inflorescences appear to conform to a fundamental body plan. The ultimate bud on the inflorescence of Limnocharis flava always forms a vegetative shoot, and the inflorescence may also produce supernumerary vegetative buds. Butomus umbellatus and Limnocharis flava exhibit a high degree of mirror image symmetry.     

Control of bud inhibition in Cyperus

Summary The axillary buds in the leaf crown of Cyperus alternifolius seedlings remain completely inhibited although the shoot is determinate and has no active apex. Buds can be released by detachment of the crown from the plant or by direct application of aqueous enzyladenine (BA), and grow out as inflorescences or vegetative shoots. These arise from activated growth centers of the primordial reproductive branch system which is enclosed within the prophyll of the inhibited bud. Buds are also released by the growth retardant, (2-chloroethyl) trimethylammonium chloride (CCC). Gibberellic acid maintains bud inhibition in detached crowns and inhibits bud release caused by CCC or BA. Naphthaleneacetic acid somewhat reduces BA-induced bud release and causes abnormal root proliferation in CCC-treated crowns. It is suggested that a high level of gibberellin within the crown, possibly in relation to a low level of cytokinin, maintains bud inhibition.     

A New Lanternshark <Emphasis Type="Italic">Etmopterus splendidus</Emphasis> from the East China Sea and Java Sea

A new species of the lanternshark Etmopterus splendidus is described. This new species is distinguished from the congeners by the combination of the following characters: distance from snout tip to 1st dorsal spine much less than distance from the spine to upper caudal origin; caudal fin short, much less than head length; dermal denticles on lateral side of trunk with very small, erect thornlike, conical crowns, those on trunk arranged in regular longitudinal rows, and distinctly arranged on interdorsal area and on lateral trunk of interspace between 2nd dorsal and caudal, but not arranged in regular longitudinal rows on dorsal surface of interorbital and o abdomen; color in life purplish-black above and with inconspicuous bluish-black flank marks and three other bluish-black marks at base of caudal fin and along its axis; shape of flank marks narrow anterior to, but broader posterior to pelvic fins.     

Suppression of growth and death of meristematic tissues in <Emphasis Type="Italic">Abies sachalinensis</Emphasis> under strong shading: comparisons between the terminal bud,the terminally lateral bud and the stem cambium

The suppression of apical growth and radial trunk growth in trees under shade is a key factor in the competition mechanism among individuals in natural and artificial forests. However, the timing of apical and radial growth suppression after shading and the physiological processes involved have not been evaluated precisely. Twenty-one Abies sachalinensis seedlings of 5-years-old were shaded artificially under a relative light intensity of 5% for 70 days from August 1, and the histological changes of the terminal bud and terminally lateral bud of terminal leader and the cambial zone of the trunk base were analyzed periodically. In shade-grown trees, cell death of the leaf primordia in a terminal bud of terminal leader was observed in one of the three samples after 56 and 70 days of shading, whereas the leaf primordia in a terminal bud of terminal leader in all open-grown trees survived until the end of the experiment. In addition, the leaf primordia of the terminally lateral buds of terminal leader retained their cell nuclei until the end of the experiment. No histological changes were observed in the cambial cells after shading, but the shade-grown trees had less cambial activity than the open-grown trees through the experiment. Strong shading appeared to inhibit the formation and survival of cells in the terminal bud of terminal leader rather than the terminally lateral buds of terminal leader and the cambium. The suppression of the terminal bud growth and elongation of the surviving lateral buds would result in an umbrella-shaped crown under shade.     

Shoot preformation in clones of Fraxinus pennsylvanica in relation to site and year of bud formation

Summary Shoot preformation was investigated in buds of four clones of Fraxinus pennsylvanica var. subintegerrima (Vahl) Fern. at two sites in Manitoba in the second (1988) and third (1989) growing seasons after grafting. More preformed primordia were produced in terminal buds in 1989 compared to 1988 at each site. Both terminal and lateral buds at Morden contained significantly more primordia than those at Winnipeg. The numbers of preformed primordia were significantly different among clones. Clone 3 produced the most and clone 1 the fewest primordia in terminal buds. Despite quantitative variation, the pattern was similar among clones for terminal buds at each site and in each year. A similar pattern was evident for lateral buds at the Winnipeg site in 1989 but at Morden, clones 4 and 1 had the largest number of preformed primordia. Data from 1989 revealed that numbers of primordia were correlated with bud dimensions, parent shoot length, diameter and number of leaves, and location of the bud on the parent. Shoot dry weight was also related to these variables and revealed a non-linear increase in dry weight with shoot length. Multiple regression, with parent shoot length and location of buds along the parent axis as independent variables provided a reliable indicator of preformation in the crown. Although there is a genotypic component to preformation, variation between sites, years and crown locations suggests plasticity in bud development.     

Growth pattern ofAbies mariesii saplings under conditions of open-growth and suppression

The growth pattern was analysed forAbies mariesii Mast. saplings in the subalpine climax forests of the northern Yatsugatake Mountains, Central Japan. The lateral branches were distinguished from the trunk not only with respect to the branching habits and needle arrangement but also with respect to the distribution of dry matter to needles, the slenderness of shoot-stem and the longevity of needles on them. Based on these differences, the contribution of the trunk and lateral branches to the matter production function of saplings is discussed. The lateral branches showed plastic changes in their growth characters in order to expand and maintain an assimilation system effectively, under conditions of suppression. In addition, the trunk growth was inhibited compared with the lateral branch growth and the apical dominance among lateral branches was weakened in the suppressed saplings. It was concluded that these growth habits resulted in the observed difference in the crown shape of saplings in the different habitats. Arguments are presented regarding the adaptive meanings of such a growth pattern for the shade tolerance and survival of the saplings and for the regeneration of the forest.     

Two Geometrical Models of Branching of Botanical Trees

A botanical tree may be regarded as a system of axes which developby repeated bifurcation. A complicated tree can be describedby a few parameters of bifurcation which determine the geometryof the bifurcation process. A bifurcation model (H-model) haspreviously been proposed and shown to be useful for comparisonwith trees which have branch complexes which approach a horizontalplane (e.g. Terminalia). Another bifurcation model (P-model)is now proposed which is appropriate to branching systems inwhich successive branch planes are perpendicular to each other(e.g. Cameraria and Tabernaemontana of the Apocynaceae). Bymodification of the P-model to take into account a geotropiceffect, a more realistic branching model for one kind of treespecies is produced. The relationship among these geometricalmodels of branching is discussed and illustrated with computersimulations. computer simulations, tree crown geometry, branching patterns, bifurcation models, Terminalia, Cameraria latifolia, Tabernaemontana, sp     

AXILLARY AND DICHOTOMOUS BRANCHING IN THE PALM CHAMAEDOREA

In both Chamaedorea seifrizii Burret and C. cataractarum Martius each adult foliage leaf subtends one axillary bud. The proximal buds in C. seifrizii are always vegetative, producing branches (= new shoots or suckers); and the distal buds on a shoot are always reproductive, producing inflorescences. The prophyll and first few scale leaves of a vegetative branch lack buds. Transitional leaves subtend vegetative buds and adult leaves subtend reproductive buds. Both types of buds are first initiated in the axil of the second or third leaf primordia from the apex, P2 or P3. Later development of both types of bud tends to be more on the adaxial surface of the subtending leaf base than on the shoot axis. Axillary buds of C. cataractarum are similarly initiated in the axil of P2 or P3 and also have an insertion that is more foliar than cauline. However, all buds develop as inflorescences. Vegetative branches arise irregularly by a division of the apex within an enclosing leaf (= P1). A typical inflorescence bud is initiated in the axil of the enclosing leaf when it is in the position of P2 and when each new branch has initiated its own P1. No scale leaves are produced by either branch and the morphological relationship among branches and the enclosing leaf varies. Often the branches are unequal and the enclosing leaf is fasciated. The vegetative branching in C. cataractarum is considered to be developmentally a true dichotomy and is compared with other examples of dichotomous (= terminal) branching in the Angiospermae.     

Branch construction and bud defence status at the canopy surface of a West African rainforest

Branch specimens were collected from the very tops of tropical tree crowns in southern Cameroon, West Africa. An analysis of branching patterns revealed a consistency of form across unrelated taxa. All specimens showed evidence of rhythmic growth cither due to the regular occurrence of dormant terminal buds or due to sympodial growth with loss or flowering of terminal buds. Study of bud anatomy revealed an extensive array of protective devices associated with drought tolerance and herbivore defence. Normally a considerable excess of dormant, well protected axillary buds were present which (almost without exception) existed in a viable state. In very many instances the large dormant bud population was due to the presence of accessory buds, i.e. > 1 bud in the axil of each leaf. The microclimate at the outer surface of a tropical rainforest may experience a daily increase in temperature and associated depression in humidity; the canopy surface characteristics are more akin to chaparral shrub vegetation than to familiar rainforest understorey vegetation.