Credit: Pixabay

The holiday season is a time when whole nuts are sure to make an appearance in supermarkets and other retail outlets. From a traditional perspective, this is logical since most nuts ripen in the fall. The holiday season is one of the few times of the year when consumers can see what a nut looks like in nature. Most often they are purchased with the shells removed and ready for use. One of the nuts likely to be found in the bin or bag of mixed nuts is the filbert.

A bin of mixed whole nuts is a common sight in supermarkets during the holiday season. Credit: Pixabay

From a botanical standpoint, a nut is a fruit (i.e., ripened ovary) consisting of a hard or tough shell which surrounds an edible kernel. Here's a good question for your next game of trivial pursuit. If walnuts are called walnuts and chestnuts are referred to as chestnuts, why are hazelnuts called filberts? The answer lies in the time of the year filberts are gathered and a 7th century saint from the country of France.

The feast day for St. Philibert of Jumiéges, a 7th century Benedictine abbot and bishop who lived in France, is held on August 20th. The date happens to correspond closely to the time of the year when the nuts of European hazelnut ripen and are harvested. When the Normans conquered England in 1066, they called the nuts of the hazel tree "philbers," in honor of the saint. This term eventually was corrupted to "filbert," which remains our modern designation.

Alternatively, some historians believe the term filbert was derived from the German vollbart which, literally interpreted "full beard." The latter is descriptive of the husked shell of the hazelnut.

Regardless of the name given to it, this nut has been popular for centuries. According to an ancient (28th century B.C.) manuscript found in China, the filbert took its place among the five sacred nourishments God bestowed on human beings. Historically, in addition to being a food source, the filbert was used as a medicine and a tonic. More than 1,800 years ago, Dioscorides (c. 40-90 A.D.), a Greek physician, pharmacologist, and botanist, heralded the virtues of the filbert in his five-volume work titled De materia medica ("On Medical Material").

He wrote, "It cures chronic coughing if pounded filbert is eaten with honey. Cooked filbert mixed with black pepper cures the cold. If the ointment produced by mashing burnt filbert shells in suet is smeared on the head where hair does not grow due to normal baldness or to some disease, hair will come again."

In general terms, the word filbert is used to refer to any of the nuts derived from species of the plant genus Corylus. The latter is a genus of 13 polymorphic species of deciduous trees and large shrubs native to the temperate regions of the Northern Hemisphere.Although it is correct to use the two designations (i.e., hazelnut and filbert) interchangeably, filbert most often is the name given to the fruit of Corylus avellana, a species native to Europe and western Asia.

Most often, filbert is the name given to the fruit of the European hazel tree. Credit: Pixabay

There are several different hazelnut species grown in the United States. One is a native plant, while the other species was imported from Europe. Both are members of the Betulaceae plant family which makes them close relatives to birch trees. They are monecious plants which means they produce both male and female flowers on the same plant. The male flowers are long catkins that appear very early in the spring. The female flowers are small, inconspicuous, and red in color. Since they also appear very early, spring frosts often damage flowers and prevents nut production. Male and female flowers do not develop at the same time on a single plant, which helps to ensure cross-pollination which is caused by wind.

Catkins or male flowers of American hazelnut. Credit: Pixabay

Corylus americana, or American hazelnut, is native to Missouri and a vast area of the U.S. stretching from Maine to Oklahoma. It tolerates many different sites, but most often is found along woodland borders. The American hazelnut is a large, multi-stemmed bush that reaches a mature height of between 10 to 15 feet. Although smaller in size, the flavor of nuts from the American hazelnut is similar to that of its European cousin. Unfortunately, it often is a bit difficult to find nuts from native plants in the wild since they are highly prized by squirrels.

The filbert, or hazelnut, available for purchase at supermarkets and other retail outlets most often is the above-mentioned European hazelnut (Corylus avellana). In the United States, this species is commercially produced primarily in relatively mild regions of the pacific northwest and is not a successful crop in other parts of our country. Oregon has an ideal climate for hazelnut growth and produces about 95% of the U.S. crop.

Harvesting nuts in commercial hazelnut orchard. Credit: Pixabay

Hazelnuts have a sweet but somewhat "earthy" flavor and can be consumer raw, roasted or ground into a paste. Their taste is attributed to a compound known as filbertone which is the principal flavor compound of hazelnut. Rich in protein, dietary fiber and unsaturated fat, hazelnuts also contain vitamin E and thiamine as well as essential mineral elements such as copper, magnesium, and manganese. Possible health benefits from hazelnut consumption include regulating blood pressure, reducing inflammation, and improving blood sugar and fat levels. Additionally, hazelnuts provide significant amounts of antioxidants which help to protect the body from oxidative stress and cell damage.

Gardeners wanting to attempt growing hazelnuts at home would be wise to choose a cultivar of American hazelnut selected to withstand colder climates. 'Rush' and 'Winkler' are two possibilities for Missouri. Recently, a number of inter-specific hybrids with C. americana as one parent to impart cold hardiness and disease resistance have been developed and are under evaluation for commercial production in the Midwest.

Hazelnuts require well-drained soil and should not be located in "frost pockets." Upper areas of slopes with good air drainage are best. Plants tolerate full sun, but also are well suited to light shade. When planting a named cultivar, remember that at least two different cultivars are needed for proper cross-pollination. Well-tended plants should begin nut production during their third year of growth, weather permitting.

As ornamental landscape plant, American hazelnut produces attractive leaves and (normally) good fall color. It tolerates a variety of conditions, attracts wildlife, and is showy much of the year. Excellent for naturalizing, woodland gardens and shade areas, it makes a good hedge or screen in informal plantings, where it can spread into a thicket. If a single specimen plant is preferred, remove the root suckers of the that arise near its base. Mature plants reach a height of nearly 10 feet.

Fall color of American hazelnut leaves. Credit: GroNative.org

Hazelnut trivia

• Ancient Romans used torches made of branches of hazelnut trees during wedding ceremonies with the belief that hazelnut ensures a long and happy marriage.
• Divining rods used to locate underground springs, buried treasure, minerals, and ores were often made from Y-shaped hazelnut branches.
• In Germanic countries, hazelnuts were ground into flour for preparing cakes.
• June 1st is National Hazelnut Cake Day.
• The hazelnut became Oregon's official State Nut in 1989.
• Worldwide, 748.000 metric tons of hazelnuts are produced each year.
• Turkey is the largest producer of hazelnuts in the world with approximately 75% of worldwide production.
• The Ferrero Group, maker of the bread spread Nutella®, uses 25% of the global supply of hazelnuts.

Ground hazelnuts combined with chocolate is a popular bread spread. Credit: Pixabay