Cabernet Sauvignon is a variety of red grape mainly used for wine production, and is, along with Chardonnay, one of the most widely-planted of the world's grape varieties.The principal grape in many Bordeaux wines, it is grown in most of the world's wine regions, although it requires a long growing season to ripen properly and gives low yields. Many of the red wines regarded as among the world's greatest, such as Red Bordeaux, are predominantly made from Cabernet Sauvignon grapes. World-class examples can improve for decades, and remain drinkable for a century. The particularly thick skin of the Cabernet Sauvignon grape results in wines that can be high in tannin which provides both structure and ageability. This varietal, while frequently aromatic and with an attractive finish, also tends to lack mid-palate richness and so is often blended with lower tannin, but "fleshy" tasting grapes, particularly Merlot and, especially in Australia, Shiraz / Syrah. Cabernet Franc is often used in blends with Cabernet Sauvignon to add aromatics. As a group, Cabernet Sauvignon wines are generally full-flavored, with a stronger flavor than Merlot for instance, and with a smooth and lingering "finish". Cabernet Sauvignon has a well defined aroma. In Old World wines, particularly those made in Bordeaux, this is characterised by a smell of violets, blackcurrant, cedar and spice. New World wines of this grape can often share the aromas of their Old World counterparts, but are more often dominated by aromas of chocolate, ripe jammy berries, oak, pepper and earth. In Australia, there is often a strong smell of eucalyptus, particularly in wines made in Coonawarra. One of the most characteristic aromas of warm-climate examples is cassis (blackcurrant), while cherry and other red berry notes are not uncommon. Cooler-climate examples often reveal greener, herbaceous notes, such as eucalyptus or green pepper/capsicum. There is, however, a great deal of variation in flavor depending on the region, winemaking technique, seasonal weather, and bottle age. Nonetheless the wines retain a remarkable ability to be recognizably Cabernet. Cabernet Sauvignon, like all noble wine grape varieties, is of the species Vitis vinifera, and genetic studies in the 1997 indicated it is the result of a cross between Cabernet Franc and Sauvignon Blanc.