Let’s say you bought some Cabernet Sauvignon vines from a local nursery to plant a vineyard. You decided on Cabernet because you determined that this particular grape variety would be best for your location because of its soil type, sun exposure and climate. But then a worrisome thought enters your head: What if the vines aren’t Cabernet Sauvignon after all, but some other less-suited variety? What if the nursery somehow got them mixed up with Sauvignon Blanc vines? That would be a mighty costly mistake.
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You could pray, sweat and grind your teeth until the first grape clusters appear, and then wait some more until they change color and mature enough for you to figure out the vines’ true identity. Or, you could call an ampelographer.
Ampelography is a type of grapevine botany that uses the physical traits of grape leaves to identify varieties. Grape leaves vary quite a bit between varieties, so a skilled ampelographer can easily distinguish Cabernet Sauvignon from Cabernet Franc.
In the world of ampelography, it would be hard to find a more renowned practitioner than Virginia-based vineyard consultant Lucie Morton, who travels around the country lending her expertise to grape growers and vintners.
Among Morton’s clients is one of California’s best Sauvignon Blanc producers, St. Supéry Estate Vineyards & Winery, which flew her out to the Napa Valley earlier this month to teach an ampelography class. I was lucky enough to participate in the workshop, and learn some tips from a master.
Before taking us into the vineyard, Morton explained the background and basics of vine identification. Lesson number one: “Looking at clusters is cheating.”
In the early days of the California wine industry, American vintners often brought back vine cuttings from Europe to plant in their vineyards. Sometimes, the varieties were not identified correctly, or were known in their native country by a different name than the one used by the rest of the world.
In the 1970s Morton began to discover that some vines planted in American vineyards were misidentified. For example, she said, in the Finger Lakes region of New York people used to say that the Chardonnay grown there tasted “Germanic,” due to the area’s cold climate. The real reason was because their “Chardonnay” was actually Riesling.
Up until the early 80s, nearly all of the “Pinot Blanc” planted in California was not Pinot Blanc but a French variety called Melon de Bourgogne. An ampelographer — Morton’s teacher, Pierre Galet — set the record straight. “It does not make you popular, pointing out other people’s mistakes,” Morton told the class.
Even so, her skills are in demand, even in the modern world of high-tech viticulture. Although DNA testing can identify varieties, Morton pointed out, it can’t distinguish between clones. Ampelography can. “There’s still practical value in this skill,” she said.
Anatomy of a grape leaf
According to Morton, the main characteristics that distinguish grape leaves include:
Lobes: If you imagine the leaf as a hand, the lobes would be the individual fingers that extend outward. Some leaves have prominent lobes, other leaves are shield-shaped and have none.
Petiolar sinus: This is the empty space surrounding the stem of the leaf. Some sinuses are wide open, others are very narrow.
Teeth: These are the serrations on the outside edge of the leaf. Some are jagged and sharp, others are rounded.
It’s also important to look at the color and texture of the leaves.
In the vineyard
Providing each of us with a list of defining characteristics for several different grape varieties, Morton sent us out into St. Supery’s Dollarhide vineyard and challenged us to bring her back a leaf from each variety. If we got it wrong, we went back to try again.
Identifying the vines was more difficult than I expected. In a given vineyard row, not all of the leaves are identical, even among the same variety. Just when I would think I had a match, I’d notice that one of the distinguishing elements wasn’t quite right: The teeth were rounded instead of triangular or the surface was smooth instead of leathery. Each time I was sent back for another leaf, I came to respect Morton’s skill a little more.
Following are the characteristics of five of California’s most popular grape varieties:
Morton calls this leaf the “monkey face” or the “mask,” because when held with its tip facing up, it looks like it has eye and mouth holes. It has five lobes, rounded teeth and an open (or naked) petiolar sinus.
This is a shield-shaped leaf, with shallow, sawblade-like teeth and an open petiolar sinus. The vine’s young shoots will have red nodes that are distinctive to Chardonnay.
This leaf is longer than it is wide, with five prominent lobes, an open petiolar sinus and deep triangular teeth. It’s yellowish in color, with a waffled, leathery texture.
This five-lobed leaf is green in color, with a wavy texture. It has a narrow, almost-closed petiolar sinus, a round shape and rounded teeth. The lobes have three prominent troughs that resemble spouts from a fountain.
This leaf is a heart-shaped shield, with a relatively narrow petiolar sinus and shallow pointy teeth. It has a puffy, quilted look and a thick, leathery texture.
Main photo: In a sea of vines, ampelography can help growers tell which grape varieties are which. Credit: Copyright 2017 Tina Caputo