Growth Ring Boundaries Research Articles

The relationship between leaf longevity and growth ring markedness in modern conifer woods and its implications for palaeoclimatic studies

Growth rings in modern conifer woods were quantitatively analysed to investigate the relationship between leaf longevity and the markedness of the growth ring boundary. Five conifer species exhibiting a wide range of Leaf Retention Times (LRTs) were examined in anatomical sections stored in the Jodrell Laboratory, Royal Botanic Gardens, Kew, Surrey, UK. The species studied were Larix decidua Mill. (deciduous), Pinus sylvestris L. (LRT=1–3 years), Picea abies (L.) H. Karst. (LRT=3–5 years), Cedrus libani A. Rich. (LRT=3–6 years), and Araucaria araucana (Molina) K. Koch (LRT=3–15 years). Two aspects of ring markedness were quantified: (1) the percentage of latewood in each growth ring increment and (2) the difference between the maximum and minimum radial cell diameters in the growth ring increment expressed as a percentage of the maximum cell diameter (percentage diminution). The product of these two parameters was calculated to give a Ring Markedness Index (RMI). Five growth ring increments were measured for each species from poorly provenanced specimens grown in southern England. Statistical analysis of these data shows that there is a significant inverse linear relationship between median LRT and percentage latewood ( R 2=0.86), percentage diminution ( R 2=0.77), and RMI ( R 2=0.91), at P<0.001. These data suggest that leaf longevity exerts an important control on growth ring markedness, in addition to the influence exerted by the growing environment (climatic and edaphic conditions). The significance of these results for the palaeoclimatic analysis of growth rings in fossil woods is discussed with reference to two case-studies: (1) the Early Carboniferous tropical climate of the British Isles and (2) the Early Cretaceous polar climate of the Antarctic Peninsula.

Organic Crystals in the Tracheids of Torreya Yunnanensis

Organic crystals were found in tracheid lumina of some samples of Torreya yunnanensis Chen ' L. K. Fu imported from Yunnan, China. Tracheids with crystals were found in short to long tangential bands along the growth ring boundaries. Because the crystals were rapidly dissolved with ethanol and xylene, cross and tangential sections were mounted in de-ionized water without staining and observed by biological, polarised light, and phase-contrast microscopy. The crystals were sublimated under vacuum during routine sample preparation for conventional SEM and only the peripheral parts remained. With the aid of low vacuum-SEM and modified cryo-SEM procedure, the shape of the crystals was revealed. Some were styloid and large enough to fill tracheid lumina, while others were stacked appearing as slates filling tracheid lumina. X-ray diffraction applied to sections and isolated crystals showed that they were single crystals and orientated along the cell wall. UV spectra on isolated crystals and methanol dissolution of crystals suggested that they were composed of phenolic compounds. Crystals that were recrystallized from methanol were analysed by 1H and l3C nuclear magnetic resonance spectroscopy. These two techniques revealed that the major and minor components were o-methoxy cinnamic acid and o-methoxy cinnamic aldehyde.

Anatomy of Stem Hyperplasia Called Tokkuri Disease in Chamaecyparis Obtusa

The stem hyperplasia called tokkuri-disease in Japan was observed on the lower part of stems of 25-29-year-old Chamaecyparis obtusa trees. The anatomy of the hyperplastic portions was characterised by rapid proliferation of the cambium, short and thin-walled tracheids, a large number of multiseriate rays, and thickened bark. The cambial activity in the hyperplastic portion was high in July and remained high until mid-October. Transverse sections show the hyperplastic portions of the cambium and growth ring boundaries are sinuous, whereas those in non-hyperplastic portions of the same trees or in normal trees are not. The sinuosity of cambia was closely related with cambial activity. The ecological and physiological causes of stem hyperplasia are discussed on the basis of anatomical studies.

Wood anatomy of the dicotyledons indigenous to New Zealand 22. Proteaceae

Abstract Wood anatomy of Toronia toru (A. Cunn.) L. Johnson & B. Briggs and Knightia excelsa R. Br. is described. Knightia is readily distinguished from Toronia by the festooned arrangement of vessels and axial parenchyma, fewer and wider vessels, markedly large rays, and absence from vessels of both helical thickenings and vestured pits. Growth-ring boundaries in Knightia are indicated by marked noding of wide rays. Fine helical thickenings are present in some fibre-tracheids of Toronia and Knightia. Fusiform parenchyma cells lacking storied structure are recorded in Toronia. Vestured pits are recorded in vessels and fibre-tracheids of several Australian species of Persoonia sensu stricto, and the segregate genera Acidonia and Pycnonia.

Lignin Distribution During Latewood Formation in Pinus Radiata D. Don

Lignin distribution during formation of latewood tracheids in Pinus radiata, was determined by quantitative interference microscopy, and by potassium permanganate staining combined with transmission electron microscopy. Lignin distribution varied among trees sampled on the same date in late winter. In one tree, latewood tracheids were fully lignified up to the growth ring boundary. However in most trees sampled, latewood was only partially lignified. The extent of lignification varied from tree to tree but in all cases, at least some lignin was present in the middle lamella and primary wall at the growth ring boundary. Latewood was ideal for examining the lignification process because of the large number of different stages present in a single specimen.

Aggregate Rays in New Zealand Nothofagus Blume (Fagaceae) Stem Wood and their Influence on Vessel Distribution

Aggregate rays occur in the stem wood of Nothofagus solandri var. cliffortioides (Hook. f.) Poole (mountain beech), N. solandri var. solandri (Hook. f.) Gerst. (black beech), N. truncata (Col.) Ckn. (hard beech), and N. fusca (Hook. f.) Gerst. (red beech), but not in N. menziesii (Hook. f.) Gerst. (silver beech). The composite structures visible in transversely sawn wood consist of groups of narrow xylem rays separated by fibres; vessels are frequently absent. The influence of aggregate rays on vessei distribution was studied using scanning electron microscopy and tested statistically. Indented growth ring boundaries are associated with the presence of aggregate rays. Aggregate rays occur in saplings. In larger trees aggregate rays taper out beyond 6 cm from the stem centre.

Seasonal Production of Secondary Xylem in the Twigs of Certain Tropical Trees

Secondary xylem production in four deciduous (Albizzia lebbeck, Dalbergia sissoo, Tectona grandis, Terminalia crenulata) and three evergreen trees (Calophyllum inophyllum, Mangifera indica, Morinda tinctoria) is briefly described. The total duration of xylem production in a year has been analysed. In three of the four deciduous trees there were two periods of xylem production in correspondence with the presence of two flushes of cambial activity and sprouting of new vegetative buds and foliage formation . In Tectona grandis and in all the three evergreen species studied there was only one period of xylem production. Periodicity in the production of different components of xylem tissue as well as the difference in the dimensions of the different xylem elements produced during each flush of cambial activity resulted in detectable growth ring boundaries within the xylem. Conspicuous changes were found in the starch and crystal contents of xylem cells adjacent to the cambial zone during the initiation and cessation of cambial activity .

Wood anatomy of the dicotyledons indigenous to New Zealand 15. Fagaceae

Abstract The wood anatomy of Nothofagus menziesii (Hook, f.) Oerst., N. fusca (Hook, f.) Oerst., N. truncala (Col.) Ckn., N. solandri (Hook, f.) Oerst. var. solandri, and N. solandri var. cliffortioides (Hook, f.) Poole, is described. The wood is diffuse-porous to semi-ring-porous with distinct growth-rings. Vessels are solitary and in multiples, mainly of the radial type. Perforation plates are simple but some scalariform and reticulate plates also occur. Intervessel pits are alternate, opposite, and scalariform. Minute projections from cell wall into lumen are sometimes present in the tips of vessel elements. Vessel-ray pits are usually confined to ray margins and are round, oval, and radially elongated with or without border. Axial parenchyma is scarce and mostly confined to growth-ring boundaries. Polygonal crystals are occasionally present in axial parenchyma. Rays are heterogeneous and 1–2(3) cells wide. Fibres are sometimes septate. Tracheids are present in late-wood. The presence of silica grains ...

Intra-increment variation in specific gravity of wood in blue pine

Intra-increment variation in specific gravity of wood is studied in relation to the types of annual increments in Pinus wallichiana. In the normal annual increments specific gravity increases almost linearly across the ring, displaying minimum value in the first-formed earlywood and maximum value in the last-formed latewood. The occurrence of false rings and that of compression wood in an annual ring causes a localized increase in specific gravity. The change in specific gravity at the false growth ring boundary is slight and gradual, whereas at the true annual rings boundary the change is steep and abrupt. The specific gravity in the first-formed earlywood portion gives the most consistent value as compared to whole earlywood, whole latewood and whole ring when studied around the circumference.