Grapes (Vitis spp.)

A muscadine grape (Vitis rotundifolia 'Alachua')
Credit: Ali Sarkhosh, UF/IFAS

Florida's grapes

There are six species of grapes that are native to Florida, while some have small ranges, grapes are found in all parts of the state. 

- Summer grape (Vitis aestivalis)
- Florida grape (Vitis cinerea var. floridana)
- Catbird grape (Vitis palmata)
- Muscadine (Vitis rotundifolia)
- Calloose grape (Vitis shuttleworthii)
- Frost grape (Vitis vulpina)

The muscadine grape is native to all of Florida and from Delaware to eastern Texas. This is grown as a sustainable crop in Florida and has been bred so that this normally dioecious plant (with separate male and female plants) is self-fertile or monoecious.

In nature, these vines are either female or male, and only the female vines set fruit. Before there were self-fertile flowers, vineyards were planted with the female fruiting cultivars, and male plants were interspersed to pollinate the female vines. Thus, production was reduced because the male vines produce no fruit. (See below.)

Fortunately, a few muscadine grape vines that had self-fertile flowers were discovered, and through breeding, this trait was introduced into new cultivars with good berry quality. This meant that self-fertile vines could be used to pollinate the female cultivars, and berries could be harvested from the entire vineyard.

Read this UF/IFAS article for extreme details on this grape and how it's grown. 

There are also several other genera in the grape family that are native to Florida, but one that is probably most familiar and widespread is the Virginia creeper (Parthenocissus quinquefolia), which is also a vigorous vine. Virginia creeper has reliable red fall color and its fruits are good food for the birds, but not so much for us. 

Grapes around the world

The grape inflorescences are borne only on new wood and each one is opposite a leaf on the vine.

There are about 80 species of grape (Vitis spp.) around the world.

Grape vines produce their bunches of flowers (inflorescences) only on new wood and each inflorescence is opposite a leaf on the vine, which is somewhat unusual in the plant world. We have some grape vines growing wild in our yard in the wooded areas, but I have never seen a flower or a fruit, because the vines grow high into the trees and their new wood is out of sight at the tops of the trees. Also, I have no idea whether my vines are male or female. For us, the grapes, while being native, are usually treated as pest plants and are cut away from shrubs and small trees so they can grow without being covered or strangled by grapes and other vines.

The people who manage vineyards cut back the flower-producing parts of the vines after harvest each year so the new growth or the new wood is produced within reach on a trellis of some type. This pruning is an art and a science to maximize the flowering and harvest. 

There are about 80 grape species around the world, but almost all of the grape vineyards grow various cultivars of the monoecious European grape (Vitis vinifera). Even the Latin name says it's the wine grape, because people were producing wines from this grape long before Carl Linnaeus began naming the plants.  

The European grape

The European grape (Vitis vinifera) makes up most of the grape production around the world.

The European grape (Vitis vinifera) is monoecious or self-fertile because each flower has male and female parts.

Self-fertilization is important in vineyards because every vine bears fruit. If you had a dioecious species, the male vines would be necessary for pollination and would require space and irrigation, but they would not add to the harvest. 

More than 3500 years ago 2 mutations turned of the production of pigment (anthocyanins) in the European grape, which resulted in the green or white grape. 

In the 1850s British botanists brought American grapes
 to England, but they were infested with a louse that
carries a fungus, which devastated the grape vineyards
all over Europe.

There are about 10,000 different cultivars of the European grape, but only a couple of dozen are regularly used as crops. We know that the two mutations that created the white grape occurred more than 3500 years ago, because residues of white wine were found in the tomb of Egyptian pharaoh Tutankhamen, King Tut. So it was under cultivation before then, but now the various cultivars of green grapes are big crops, especially for wine, table grapes, and raisin production.

The European grapes were heavily damaged in the 1850s.

In the 1850s, avid botanists from Victorian England collected specimens of American plants both pressed and alive, including grape vines to see if they could hybridize with the European grape. 

Unfortunately, those collected vines included a hitchhiker, the phylloxera louse, a sucking insect related to aphids. There are two larval stages: one attacks the leaves and other attacks the roots. Because phylloxera is native to North America, the native grape species there are at least partially resistant to the fungus it carries. By contrast, the European wine grape is very susceptible to the insect and the fungus, which blocks the xylem tubes. The epidemic devastated vineyards in southern Great Britain and then moved to the European mainland, destroying most of the European grape growing industry. The problem spread rapidly across the continent. Some of the early solutions were quite toxic, including the Bordeaux mix, which is a combination of copper sulfate and lime, which has now been outlawed in Europe. 

There is still no cure, but now most vineyard grapes are grafted onto resistant American grape stock, but not just one. Experimenting led to Texas grape root stock used where the European soils are chalkier, which other root stock was used elsewhere so the roots are less affected. This is important because treating the roots of an established plant for the fungus damage is difficult at best. Also, the arrangement of today’s vineyards are as a result of this epidemic. The grape vines are planted at some distance apart so the roots of each one are isolated. Then, if there’s a problem, that one plant can be removed before the fungal infection spreads. For the upper parts of the plant, fungicides are sprayed early in the season, and modern, more selective insecticides are now used to reduce the louse population. At any rate: Vintners have figured out how to be successful, because the grape production is huge across the globe. In 2022, the US produced more than 5 million metric tonnes of grapes and was only #5 in the world. China led the nations in grape production with more than 12 million metric tonnes. Italy, France and Spain were 2, 3 & 4. 

I hope that you have some grapes growing in your native landscape to feed the birds and maybe yourself.

Green Gardening Matters
Ginny Stibolt