Importance of photosynthesis for life Their ability to form organic matter from inorganic substances, mostly water and carbon dioxide, is a unique feature of green plants, algae and cyanobacteria. The majority of the life on the Earth is totally dependent on these organisms that are able to capture the energy of sunlight and convert it
Non-cell wall polysaccharides In addition to cellulose, hemicelluloses and pectins, plants contain polysaccharides that do not locate in the cell wall. These polysaccharides do not have any specific interaction with cellulose (different from ‘cellulose-like’ hemicelluloses) or necessity of forming gel-type of network structures (different from pectins and ‘cellulose-unlike’ hemicelluloses). The non-cell wall polysaccharides serve mostly
Aging of wood In living trees, the outer bark protects the phloem and xylem from exposure to sunlight, rain and dryness. Cutting and debarking of the trees lead to several changes that are important in technical and structural analysis of wood. Fresh wood cell walls contain by volume ca. 30 % water and its removal
Fungal decay of wood The relationship between plants and fungi is dualistic. Plants may benefit from living in symbiosis with certain fungi but on the other hand the biomass-degrading fungi is the biggest threat to long-living plants, especially trees. Usually, fungi enter plants from the soil where most of the fungal mass exists. Wood-degrading fungi
Plant cell wall All parts of living plants consist of varying amounts of living and dead cells. Different from animals, a cellulose-containing cell wall surrounds each living plant cell, its cell membrane and cytoplasm. When the cells die, the cell wall is basically what remains. In plants, the dead cells are not useless at all.
Plant tissue structures Plants are made of cells that specialise and organise in tissues to serve the essential living functions of the plants. The dermal tissue is a monolayer of cells that surrounds each plant throughout from the roots to the leaves. Root hairs and shoot trichomes are extensions of the dermal tissue. A thin,
Wood bark Bark comprises, on average, ca. 10 % of wood stems. In young trees, the inner bark, phloem, is dominant but in older trees the share of the outer bark, rhytidome, increases. The secondary growth of the inner and outer bark takes place in the vascular cambium and cork cambium, respectively. The outer bark
Softwood xylem structure Although most of the coniferous trees are evergreen, their growth rate may vary periodically depending on the annual seasons. In cold regions, the growth ceases during the wintertime. After overwintering, the new growth is fast but it slows down towards the autumn. The periodical variation in the growth rate leads to the
Transport of water and nutrients Although plants use water as a source of hydrogen in photosynthesis, they need much more water for transporting inorganic nutrients from the soil and translocating the water-soluble photosynthesis products within the plant. In hot climates, evaporation of water through the stomata of the leaves protects them from overheating. In dry
Variation in lignin structure The structure of lignin originates from two main factors, the monomer composition and the conditions of lignification. Structural variation occurs between species, anatomical locations, cells and cell-wall layers. Although chemical linkages exist between the cell-wall polysaccharides and lignin, certain organic solvents can solubilise it from disintegrated cells and cell walls in
