The science bit
High climbing vine, with stems up to 35m long in the wild but usually cultivated at around 1–3m. Bark flaky. Tendrils growing opposite leaves. Leaves palmately lobed, hairy/bristly on underside. Flowers form in dense panicles that develop into bunches of berries (‘grapes’). Pollinated by wind, insects and self-pollination.
- Wild grapes thrived in the warm, damp, wooded lowland valleys from Turkestan, deep in Asia, through Armenia into Thrace.
- Vine cultivation and wine production kicked off in Armenia. It then spread to Eqypt and Phoenicia and around 4,000 years ago to Greece. The Greeks took the art of viticulture around the Mediterranean and the Romans spread the knowledge up the river valleys into France and Germany.
- Water is a precious resource and vineyards use a lot of it, but experiments are being conducted in Australia where roots on one side of the vine are kept in dry soil while roots on the other side are irrigated. The process is then reversed. This results in less side shoots and more grapes, which requires less pruning and offers savings in money and water.
Where it grows
Found only in cultivation mostly in south and central Europe, and other places around the world with similar climatic conditions. The soil composition of vineyards is very important as not only does it support the root structure of the vine but also influences the drainage levels and amount of minerals and nutrients that the vine is exposed to. The ideal soil will have thin layers of topsoil and subsoil, which can retain water but also allow it to drain away readily. Heat retention is also a sought-after trait as it helps with the fruit-ripening process.
Grapes are eaten fresh and dried. Sultanas are soft, juicy amber-coloured fruits with a sweet flavour produced from seedless white grapes, mainly Thompson Seedless. Raisins are dark brown and wrinkled with a sweet mellow flavour. Currants are dried, black seedless grapes from a variety called Corinth, grown in Greece for more than 2,000 years.
Grape juice is widely drunk and, of course, used to make wine. The strong glass bottles with corks developed in the 17th century were the key to the type of wines we produce today. Although grapes are mostly crushed mechanically these days, they are still crushed by foot in some areas. Years ago the sugars in the grape juice were turned to alcohol by the yeast on the skins; today things are carefully controlled. Wine is more often sterilised and the yeast added. Good wine vintages are stored for around three years in heavy wooden casks. The tannin from the oak casks helps to preserve the wine when it is bottled. One of the reasons that good wines cost so much is that these casks have to be renewed every five years.
Apart from using various grapes, different types of wine are made by adjustments in the fermentation process. Champagne is made by bottling before fermentation has finished allowing the process to finish in the bottle. Sweet wines have their fermentation brought to a premature halt by the addition of sulphur. Port is made by arresting fermentation by the addition of alcohol. Brandy, which contains the most alcohol, is made by distilling wine.
- Lobe: incomplete division in any plant organ (eg leaf).
- Palmate: when all lobes originate from a central point.
- Panicle: multi-branched collection of flowers (inflorescence).
- Tendrils: slender coiling structure.