Like all plants, we classify grapevines according to the system of taxonomy laid out by Swedish botanist Carl Linnaeus in 1753. Grapevines belong to the order called Vitales, the family called Vitaceae and the genus Vitis. The genus Vitis has about sixty different species, but one species rules the world of wine: Vitis vinifera, the Old World wine grape.
All the international grape varieties are sub-species, cultivars, of Vitis vinifera: Cabernet Sauvignon, Merlot, Pinot Noir, Syrah, Chardonnay, Sauvignon Blanc, Pinot Gris, Riesling. Add to these some dozens of other important wine grapes: Zinfandel, Sangiovese, Tempranillo, Garnacha, Albariño, Barbera, Nebbiolo, Chenin Blanc, Gewurztraminer, Cabernet Franc, Mourvedre, Malbec, Viognier, and add to these literally thousands of others, some widely grown, others hanging on in a few vineyards somewhere.
Many of these major wine grapes sub-species (or cultivars) have their own variants called “clones.” Over 100 clones of Pinot Noir exist, as an example.
What about the other fifty-nine species of Vitis other than Vitis vinifera? A good many of these species are native to North America. A prominent example is the Vitis labrusca, which we know better as the Concord grape. The Concord is great for eating out of hand, making grape juice or grape jelly, but early European settlers found that wine produced from labrusca grapes had an off taste of strawberries and wet fur, an unpleasant taste they labeled “foxy.”
“No problem,” they said. “We will bring over vinifera vines and grow them in the New World.” American founding father Thomas Jefferson was one of those people who tried. He imported Italian Sangiovese vines to grow on this Virginia estate Monticello. He also imported an Italian winemaker. No matter what Jefferson did (or ordered his slaves to do), none of these vines lived long enough to bear fruit.
In the eighteenth century, no one could figure out why non-vinifera vines thrived (but made poor quality wine) and vinifera vines didn’t make it.
The reason would become evident in the next century. The culprit was the North American vine pest called phylloxera. Phylloxera is a sap-sucking insect, akin to an aphid, which attacks grapevine roots. American vine species produce a kind of sticky sap that the aphids do not like. As a further defense, American vines form a layer of protective tissue to cover any cut the insect might cause and protect the root from dangerous fungal or bacterial infections. Vinifera vines, on the other hand, are helpless against this destroyer.
During the 1850’s, Victorian botanists imported American vines to England for their botanical gardens. The advent of the steamship shortened the ocean crossing dramatically, allowing phylloxera insects to survive among the vines. Within a few years, phylloxera destroyed every vineyard in England. It next hopped over to France. In 1863, the first French vines began to die. Over the next 25 years, phylloxera nearly wiped out French viticulture. It soon spread to the rest of Europe. Grape growers tried every method under the sun to combat the menace: copper solutions, flooding the fields, burying a live toad under each vine to “draw out the poison.” Nothing worked.
It was phylloxera that spurred horticulturalists to create hybrid vines, crossing vinifera vines with phylloxera-resistant non-vinifera vines like Vitis labrusca. The resistance to phylloxera did not seem to come across in the newly created vine, but other attributes, like resistance to winter frosts, did replicate. Hybrid vines like Seyval Blanc are still used today in cold or humid climates where vinifera vines do not thrive, in parts of New York State, Canada, Japan, and England. Many make delightful wine, but they have an image problem and it is difficult for them to compete with the powerhouse international grapes on the market.
The horticulturalists kept at it, and a solution was eventually found. If crossing grape species doesn’t work, why not graft the tops of vinifera vines (called scions) to non-vinifera roots? The DNA responsible for the actual grapes resides in the scion and not the root. Texas horticulturalist Thomas Volney Munson (1843-1913) was the great promoter of this technique (he used the wild mustang grape of north Texas for his roots). The technique worked, and the delighted French government awarded Munson the Legion d’Honneur.
Today, except in some isolated areas (particularly in Chile and Australia) where phylloxera does not reach, all commercial grapes are grafted to phylloxera resistant rootstock. Once grafting became the norm, rootstocks were developed to respond to a wide range of environmental challenges such as resistance to other diseases and pests, soil salinity, calcium content, soil acidity and alkalinity, too much water, too little water, cold resistance, heat stress, and so forth.