Pennsylvania is ripe with great grapes

In my last article, I wrote about the bounty of autumn. I focused on nuts -- walnuts and hickory nuts to be specific. From the Botany 101 part of the article you will recall that the plant parts we commonly called nuts are in botanical parlance a fruit.

Well, since it is still fall, I'll use this article to write about another fruit. This time, one that is botanically and commonly called a fruit -- the grape.

Pennsylvania's native flora includes seven species of wild grapes. The most common are summer grape ( Vitis aestivalis ), fox grape ( V. labrusca ) and frost grape ( V. riparia ).

Grapes are characterized by a woody stem that is flexible rather than stiff. Flexible stems to the botanist are vines. The bark of grape vines is composed of thin, papery, dark gray strips that easily peel off in handfuls. Dried piles of grape vine bark make a perfect tinder to start a fire from a spark.

The other distinguishing feature of grapes is that the plants have tendrils.

Tendrils can be stems, leaves or leaf stems that have been modified to be used for climbing, support or attachment by one plant to another. Grapes aren't the only plants with tendrils. The peas in your garden have tendrils that are modified leaves. Clematis, the native and garden vine, has tendrils developed from the stem of the leaf. In grapes, tendrils grow from the woody stem of the plant.

When tendrils touch a still object for long enough they begin to curl and wrap themselves around that part for support. A few plant tendrils use an adhesive rather than curling to gain a foothold.

Virginia creeper, another common native vine, and English ivy, a cultivated garden plant, use a sticky adhesive exuded from the end of minutely branched tendrils to glue themselves to trees, rocks, stone walls, and in the case of the cultivated ivy, the side of a house. If you have ever tried to pull English ivy off a brick wall you realize that the plants natural glue can be quite strong.

Wild grapes have flowers like other flowering plants. However, the spring blooms are small and inconspicuous, so they aren't easily seen. The flowers are pollinated by insects and, if everything goes well, fruits ripen in late summer.

Botanically, grapes are berries.

Again, this is one of those areas where botanical terminology differs from the supermarket or common usage. Botanically, a berry is a fleshy, several-seeded fruit developing from a single pistil (part of the female organ of a flower.) True berries, things that a botanist would call a berry, include cranberry, blueberry, gooseberry, black currant and red currant. These are plants on which your grocer would agree. However, in the botanical world the tomato, eggplant, chili pepper, avocado, grape and banana are all berries.

To make the terminology between botanists and grocers even more confusing, to the botanist things that are not berries include the strawberry, blackberry, raspberry and boysenberry. These are aggregates in the mind of the botanist.

Back to grapes.

Along with the common summer, fox and frost grapes in Pennsylvania, we have several species which are rare. Indeed, two are on the endangered species list. These are New England grape ( V. novae-angliae ), sand grape ( V. rupestris ).

New England grapes are found in moist mountain woods and ravines. Sand grapes are rare and found on riverbanks. In Western Pennsylvania, sand grapes are found along the Youghiogheny River in Ohiopyle State Park, especially along the whitewater parts of the river where the boulder strewn edges have sandy pockets. The sand is deposited during spring floods and is deep and moist through much of the year, the ideal habitat for this species.

Sand grapes have a small plant with tendrils only at the ends of the plants. Thus, the sand grape sprawls across the rocky ground. The fruit is small, but very sweet.

Other native grapes also bear fruit, and they are sweet. I tried a few of the grapes in the photograph, and they were very similar to the Concord grapes we find in the supermarket. However, wild grapes are generally smaller, somewhere between the size of a pea and a cultivated grape. They can be harvested and made into jellies, jams, pie filling and, of course, wine.

Picking grapes is a difficult task since they generally are high in the forest canopy. If you're a wild turkey, ruffed grouse, squirrel, cardinal, mockingbird or robin, then the picking is easy. Other creatures that feed on wild grapes are white-tailed deer, black bear, raccoon, skunk and opossum. These animals are more likely to be on the ground feeding on the fruits that hang low, or, because the weight of the fruit has broken a branch of the tree, are in easy reach.

Grapes supply food energy to birds and other creatures. In return, the hard seeds pass unharmed through the digestive tract of birds and bears and are planted, along with a supply of natural fertilizer, in another location. This is the way many plants are dispersed and move into new habitats and regions.

The reason I decided to write this article was because I had a question from a reader about grape vines and how to control them.

In some places, wild grapes will form large thickets or tangles. They can grow over shrubs, reach the upper branches of nearby small trees and from there, in step-ladder fashion, reach the surrounding forest canopy. Fast growing grape vines can out-compete older or diseased slower growing trees by shading their leaves and thus cutting off their food supply.

This isn't a common problem, especially in very large, unbroken forests. Dense grape invasions are more likely in places where there have been other disturbances such as logging, storm blowdown or disease that opens the tree canopy and allows grape vines to thrive.

For the most part, grape vines in a healthy forest live in harmony with the mature trees. The trees provide support for the grapes and hold their leaves high where there is plenty of sun. When the trees are healthy and growing fast enough to keep ahead of the grape vines, there is a balance between grapes and forest trees.

There is always a way to look at the natural world from a different view. When grapes do get out of control and form dense thickets, these are good cover for a wide variety of native animals, especially those who make grapes a part of their diet. We might find these thickets unsightly and worry about the impact on the forest. But it could be a case of what one neighbor (us) finds to be a problem might, in fact, be somewhere that other neighbors (robins and cardinals) find a perfect place to make a home and raise a family.