A grape is a grape, and a vine is a vine. Right? Not really. There is a variety of species of grapevines, only a fraction of which are used to produce wine, and really only one of which is used to make wine on an international scale. And within that species, Vitis vinifera, there are something like 1,000 different varietals with their own flavor and texture profiles, environmental needs, skin color, leaf shape, inclinations toward disease. It's kind of like comparing a Great Dane and a Chihuahua - they're the same species, but no one is going to confuse them for the same dog.
With grapes, the distinctions are not always so obvious. It's probably fairly easy to tell a cabernet sauvignon vine from a chardonnay vine, given that the grapes are noticeably different colors. But what about a cabernet from a merlot? This is where the science of ampelography comes in. Traditionally, this area of study compares the form and color of not only the grapes, but also the leaves on the vines, to tell one variety from another.
In the case of cabernet, it has small, thick-skinned grapes with an almost blue tint, whereas merlot grapes are larger, thinner-skinned and grow in looser bunches. Leaf shape is a little more difficult to describe without getting overly technical, but merlot leaves have a leathery surface and yellow tint lacking in cabernet, as well as sharper "teeth" (the textural pattern along the outside of the leaf).
Sometimes these already relatively subtle differences can be overlooked, to the detriment of the finished wine. A well-known example occurred in Chile, when farmers began planting both merlot and carmenère in the mid-1800s. The two varieties were often planted together in what is called a field blend. Whether the growers knew they had different varieties and the knowledge was subsequently lost or the growers thought they had all merlot is a subject of debate.
What is acknowledged, however, is that for a long while, Chilean merlot wasn't held in high esteem. It had a strong flavor of bell pepper and tasted generally green and weedy. When, in 1994, an ampelographer named J-M Bourisquot identified a large amount of Chilean merlot as actually being carmenère, it explained a lot. Merlot grapes ripen several weeks before carmenère grapes do, so growers had been harvesting their grapes far too early; hence the green, under-ripe flavors of Chilean "merlot." Once growers knew what grapes they were dealing with and began to harvest them appropriately, the quality of both Chilean merlot and carmenère improved.
2015 Vistamar Carmenère Cachapoal Valley Sepia Reserva ($11 per 750-milliliter bottle) is rich with black currants and blackberries, a spicy note of black pepper and balsam, as well as the signature whiff of tomato so often caught on the nose of a ripe Chilean carmenère. The nature of the fruits lightens a bit on the palate, with pomegranate and red berries coming to the forefront.
To compare, 2015 Vistamar Merlot Maipo Valley Sepia Reserva ($11) is weightier on the nose than the carmenère, with roasted and cured meat, blueberry jam and a fallish hint of maple and spice. On the palate, the wine becomes almost Christmasy, with flavors of spiced fruits, cherries and plum pudding.
Today, ampelography doesn't just rely on the appearance of the grape and the vine leaves. DNA research now plays a major role in grapevine identification. It has allowed experts to establish "familial" relationships between grapes, as varietals cross and form new types. For example, DNA research has established that merlot and carmenère are half-siblings, both being a cross between cabernet franc and another (in both cases, very obscure) grape variety.
DNA investigation not only illuminates relationships between grapes, but also shows when grapes grown in vastly different places - under different names - are actually the same. Such a revelation occurred between the years of 1994 and 2011, as DNA evidence first showed that the Italian grape primitivo and the grape known in the United States as zinfandel were one and the same; and later, further work indicated that the same grape had originated in Croatia, where it was known as tribidrag or crljenak kaštelanski.
While I was, unsurprisingly, unsuccessful in finding Croatian wine in New Mexico, both zinfandel and primitivo are available in abundance. 2014 Klinker Brick Zinfandel Lodi ($17) is by far the bolder of the two, as is common in zinfandel/primitivo comparisons. Zinfandel tends to be driven by dark fruits, in this case an abundance of stewed black cherry and blackberry, with a sweet note of candied violet.
2015 Caleo Salento Primitivo ($10) has plenty of fruit, too, though of a lighter tart red cherry and raspberry bent, with a hint of rose as a floral note and a meaty gravitas of leather and freshly turned earth.
While ampelography may sound like an obscure, perhaps even outmoded, area of study, in reality, it plays an active role in improving wine quality, solving age-old problems. It even occasionally has a hand in orchestrating a family reunion of grapes.