Wine-grape growers have been struggling since the days of Pliny the Elder in ancient Rome to get their varieties straight. Over the centuries, ampelography – as the science of vine identification is known – has become more sophisticated, but given the thousands of species, varieties and clones planted all over the world, it still can be a convoluted and even inaccurate process.

Take, for example, French Beaujolais, a wine primarily made from the gamay grape. Sounds simple, except that many other varieties called gamay, but which really are not gamay, are used in that wine, too. To further complicate matters, in California the variety used to make a light and fruity red wine that looks and tastes much like Beaujolais is called gamay Beaujolais – although it is really a clone of pinot noir. Gamay Beaujolais is not to be confused with a sturdy red wine called Napa Gamay (which is, in reality, made from a variety called valdiguié).

Got that?

Well, of course not. But it goes to show just how confusing wine-grape nomenclature can be. Ampelography was a hit-or-miss proposition until Professor Pierre Galet came along and began his work in the 1940s. Galet, chairman of the department of viticulture at Montpellier, the top French viticultural school, formalized the ways scientists could positively identify grapes, thus founding modern ampelography.

Galet created a system of identification based on the shape and contours of the leaves, the characteristics of growing shoots, shoot tips, petioles (stems that attach leaves to shoots), the sex of the flowers, the shape of the grape clusters, and the color, size, seediness and flavor of the grapes themselves.

The technique works fairly well when identifying varieties – that is, telling cabernet sauvignon from pinot noir, or zinfandel from chardonnay. It works less well when telling one clone – or sub-variety – from another. And it's not foolproof. Soil, climate, disease and insect damage can all alter leaf shapes, shoot growth and other characteristics, throwing ampelographers off track.

Some characteristics, especially of the grape berries, are less prone to variability. Skin color, the color of the pulp, the presence and shape of seeds, and the sex of the flowers are all qualities that change very little even when growing conditions are quite dissimilar.

Grape flavor would be another stable criterion, but it's the human palate that's unstable, as anyone who has done a great deal of wine tasting knows. Although some wine lovers pride themselves on their ability to identify a wine by aroma and taste, the human sensory ability is just not precise enough to be scientifically accurate.

And yet, with the worldwide explosion of interest in wine and the proliferation of clonal variations within varieties, it's ever more important for growers to know exactly what they're planting, for winemakers to know exactly what they're fermenting and for consumers to know exactly what they're drinking.

The folks at William Hill Winery in Napa Valley are speeding this process along by giving consumers an ampelographic lesson with their new wine labels. The Chardonnay label is die-cut in the shape of a real chardonnay leaf, the Cabernet Sauvignon label in that variety's leaf shape, and so on. Winemaker Jill Davis says "it would have been easier to have a generic grape leaf shape, but we wanted it to be accurate to suggest we're making honest wine here, and to educate the public." The die-cut labels were introduced in the fall of 1997, and Davis says they've been "extremely well received."

Ampelography has been the only scientific way to sort out all the confusion that the proliferation of new crosses and the increasing number of clones has caused. In France, ampelographers have shown that vines with different regional names turn out to be the same vine. Conversely, vines that are supposed to be of the same variety turn out to be different varieties altogether. Ampelography has been used to trace the origin of vines – scientists have traced the cabernet sauvignon vine back to its wild origin in the region around the Caspian Sea. And it has been used (so far without absolute surety) to try to determine exactly where the zinfandel grape of California originated.

Although such attempts have not met with complete success using Galet's traditional ampelographic system of identification, hope for better techniques is on the horizon. I asked Linda Bisson, professor of enology at UC-Davis, whether DNA analysis might be used to identify grape varieties.

"That is the ultimate goal, although we're not there yet," Bisson said. "It's the same technique forensic scientists use for criminal investigations. If we can find exact gene sequences that are unique to certain varieties and clones, then we should be able to use DNA analysis to determine precisely what variety or clone we're dealing with.

"The problem right now is finding those unique marker sequences," she said. "We're working on it, and I'd say that within five years we'll have it." One early result seems to indicate that zinfandel came from Croatia, where it is known as plavac mali. Eventually, then, Pierre Galet's ampelographic method will yield to the more precise method of DNA analysis. But there will always be those among us who will look at a vine leaf and say, "That's cabernet sauvignon." And, oftentimes, we'll be right.

Contributing Editor Jeff Cox is the author of From Vines to Wines and writes about wine for numerous publications, including The San Francisco Chronicle. He is also the host of "Grow It!" on the Home & Garden TV Network.

Reading Leaves – An Artist's View

No, I am not a seer or teller of fortune who peers into cups to read tea leaves to call forth clairvoyance. Rather, I am an artist who has gathered hundreds of grapevine leaves in my portfolio; each one pressed, sketched or printed. Over the years, with the assistance of viticulturists and ampelographers, my leaf collection has been the source of great inspiration – both from a creative and authentic standpoint – for wine- and grape-themed etchings and papier-mâché masks.

The term ampelography comes from two Greek words: ampelos for vine and graphe for description. Upon reading in Pierre Galet's A Practical Ampelography, translated and adapted from French into English by Lucie T. Morton, "In the genus Vitis, the leaves are almost always palmate (all main veins arising from a single point), with various shapes, sizes, and degrees of lobing," the question arises about recognizing the different characteristics of each variety.

Chardonnay leaves, with only slightly indented sinuses, remind me of round, patinated, ancient coins – harbingers, perhaps, of the gold medals that may one day be reaped in wine competitions. Cabernet sauvignon leaves appear to be heralding their nobility by flaunting distinctive, Gothic-arched edges that are often bordered in scarlet hues and pierced with graceful apertures. I will be the first to admit that ascribing anthropomorphic qualities to grape leaves proves that my artistic license overshadows my scientific knowledge, but I can't help myself.

Justin Meyer, cabernet sauvignon winegrower, co-owner of Silver Oak Cellars and author of Plain Talk About Fine Wine, explains that the cabernet leaf has "deep sinuses with a naked vein at the petiolar sinus." A petiole is the leaf stem, and the petiolar sinus is the space between the two lobes. When this opening is delineated by veins at the edge, they are described as being "naked." Meyer also points out that the cabernet leaf is one of the few varieties, along with chardonnay, that has naked veins at the petiolar sinus and then ponders the question: "Is it only coincidence that the most sought after white and most desired red varieties have this common characteristic of identification?"

"Every shoot and every fruit," wrote Leonardo da Vinci, "benefits from its leaf, which serves as the mother, giving water from the rain and moisture from the dew which falls at night from above, and protects against the too-great heat of the sun."

Modern viticulturists in hot climates appreciate and encourage leaf canopies to protect the grape clusters from sunburn. Conversely, in cool climates with less persistent sunshine, the canopy is manicured in such a way that the grapes are fully exposed to the elements of sunshine and breezes, promoting ripening and preventing rot.

Throughout history, artists have recognized the importance of leaves to life. Recurrent images of anthropomorphic leaves in the persona of "Green Man" have appeared in sculptures, masks and paintings since ancient times.

Pagan foliate heads were carved in Roman temples and even Bacchus, with his crown of grape leaves and clusters, is a variation of Green Man.

Green Man is thought by many art historians to be an archetype expressing psychic photosynthesis. Christian leaf masks with foliated tendrils emanating from mouths and nostrils, were sculpted between arches and on corbels in Gothic cathedrals throughout Europe, and also were portrayed by Renaissance artists such as Botticelli, Donatello and Michelangelo. English poet Samuel Taylor Coleridge described Green Man as one who "utters life through his mouth. His words are leaves."

Grapevines have embellished crowns and gowns in real life, as well as in sculptures and paintings. Countless are the times that a judiciously placed leaf on an otherwise nude body has enabled a painting to be accepted by priggish jurors.

Shuffling through my line drawings of grape leaves, I spot a large zinfandel leaf displaying its assertive character with deep lobes and definitively notched, Z-shaped teeth. A small pinot noir leaf, unlobed, floats over the zinfandel leaf; its narrow, lyre-shaped petiolar sinus and serrated edge contrast with the bold configurations of the zinfandel leaf. Reading these two leaves, I am reminded that while zinfandel's origins are still a bit murky, pinot noir, long a favorite of kings and clergy, can be traced back to the first century.

Walking out in the vineyard with sketchbook in hand, I enjoy being able to recognize specific grape varieties by looking closely at their leaves and focusing on their essence – ignoring the water spouts and renegade leaves. For example, merlot leaves can be identified not only by their wedge-like shapes, but also by their club-shaped, lateral sinuses – often with an extra "tooth" appearing in that space.

Of course, immediate and positive identification can be achieved when winegrowers nail signs on their fence posts to name the varieties in the vine rows. I wonder if they do this for themselves or for me?

Guest Contributor Gina Gigli is an artist and writer living in California's Sierra Nevada. When she's not reading grape leaves, she's talking to pine trees.