Leaves are the power plants of green plants and next to the roots of the main nutritional organs. At the Rebstock they form like that eyes (Summer and winter eyes), tendrils and inflorescences (Gescheine or later grapes) as lateral outgrowth at the Nodien (Knot) young growing shoots, While the shoot tip grows in length, new leaves branch off constantly, which develop according to a species- and variety-specific blueprint. With the help of leaf pigments like chlorophylls. carotenoids and flavonoids the light energy of the sun is absorbed by the leaves and during the photosynthesis under the use of carbon dioxide and water in high-energy glucose (Glucose) and oxygen transformed. The necessary carbon dioxide is released from the air through the stomata (Stomata) mostly taken on the undersides of leaves. Through these small stomata escapes the daytime produced oxygen to the outside.
Due to the water vapor saturation deficit of the air, each plant cell constantly loses water, which evaporates outwards into the air. This complex process is called evapotranspiration designated. The constant loss is compensated by the subsequent supply of water through the roots of the soil, so that a constant flow of water through the plant takes place. This transpiration allows mineral nutrient in the soil solution from the root at all up into the plant can be transported. At 100% relative humidity and water vapor saturation of the air, water is no longer physically evaporated. For such cases, a slow flow of water can be maintained via active energy-consuming pumping movements in the roots (root pressure) and droplet-wise water delivery via special pores. This osmotic pressure is called guttation (Excretion of excess water).
As Blattachsel called the angle between the stem axis and the branching off leaf. The attachment point of the petiole at the node is called leaf reason. On the petiole (Petiolus) sits the leaf blade (Lamina = leaf surface). Depending on the grape variety, the leaf margin may be undivided, notched or notched. By stronger baying arise three-, five- or siebenlappige leaves. The leaf blade is traversed by five major nerves (ribs), which branch into side nerves and outgoing net-like connected veins. Through the latter, each cell of the leaf tissue is supplied with nutrients and water and transported the sugar produced to the grapes. The leaves are next to the grapes an excellent indicator of the health status of the vine. Diseases, lack of nutrients and pest attacks are inter alia as Gallen and necrosis, as well as by discoloration or yellowing (see also under leaf diseases ).
At all nodes (nodes) one Triebes there is one sheet each. The leaves are alternate, that is arranged alternately left and right. In each Blattachsel forms a summer and a winter eye. The summer eye is already floating during the summer and forms a sting. The winter eye, however, does not drive out until the following spring and then forms the new summer shoot. There are two consecutive leaves on the opposite side of the page (and the two eyes) tendril, as a rule, the respective third leaf is free of tendrils. There are no tendrils on the lowest nodes of the shoot. In the upper part of the shoot some tendrils are replaced by inflorescences (bills). The tendrils and the bouquets are very similar in structure, so that there may be mixed forms of the two.
The variety-specific morphology of the sheet is an important criterion for the identification of varieties, Leaf size (hand to plate circumference), leaf shape, number of lobes, depth of the bay, opening width of the stalk and leaf lateral bays, type and density of the perforation, density of hair and bristles are important characteristics in the context of ampelography, The use of ampelometric criteria, such as the opening width of the apical angles between the major nerves and other measurable features, was determined by the ampelographer Hermann Goethe (1837-1911) first suggested in 1876. Before DNA analysis was the visual determination of grape varieties on the basis of morphological varietal characteristics of the only, but sufficient and to date the fastest and cheapest method. With the leaf fall in late autumn, the annual ends growth cycle of the vine. With different Deciduous care measures the leaf production is regulated. See also a list below grapevine,
Graphics: taken from Bauer / Regner / Schildberger, viticulture, ISBN: 978-3-70402284-4, Cadmos Verlag GmbH