native to: the most commonly found commercial variety is native to southern Europe and Turkey, although there is a wild hazelnut that is native to the Pacific Northwest
in season here: fall
Hazelnuts, filberts, and cobnuts are members of the birch or Betulaceae family. Cobnuts are a rounder species, while filberts are more elongated. The name “filbert” may come from the nuts’ tendency to mature around the feast day of St. Philbert, the 22nd of August; or it may be a corruption of the term “full beard,” referring to the nut’s husk. Some use the names hazelnut and filbert interchangeably while others consider them different, if very similar, nuts. Hazelnuts are a significant commercial crop in Washington and Oregon (it’s Oregon’s official State Nut), probably first introduced into Oregon by early French settlers. A century ago, railroad companies advertised the possibility of hazelnut orchards in the Northwest as part of their efforts to get people to move to this area (and have themselves and their supplies shipped in by railroad, of course). The wild hazelnut that is native to the Pacific Northwest is not very suitable for commercial production, being protected by a closer involucre or husk (this wrapping of leaves is particularly prickly in the case of our native nuts), but if you’re willing to put in the effort to harvest them, they’re perfectly edible. Most of the hazelnuts in stores are of the “Barcelona” variety and are often a year or more old, but if you can find an orchard from which to buy directly you’ll get fresher nuts and may find other varieties (Holmquist Orchards offer a variety called DuChilly that makes a good snack). The skin of hazelnuts is somewhat bitter, but can be removed after roasting by rubbing a layer of nuts in a towel (the motion would look similar to rolling out dough).
The wood of the hazel tree is sometimes used in bows, and the straight shoots make good arrow shafts; hazel wood is also a traditional choice for divining rods. The trees are a traditional choice for hedges, especially in England, and can attract butterflies. The hazelnut tree blooms in the middle of the winter and is pollinated by the wind; the nuts begin to form in June.
A Chinese manuscript from 2838 B.C.E. lists hazelnuts among the five sacred nourishments divinely bestowed on humans. In about 200 C.E., the Greek physician Dioscorides wrote of filberts that “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.”
Like other nuts, hazelnuts are good for the heart. They have high levels of folates, which may help prevent depression, and the highest proanthocyanidin content of any tree nut, making them useful in reducing the risk of blood clots, urinary tract infections, and certain kinds of birth defects. They’re high in fiber and a particularly good source of copper and manganese. They’re a bit high in fat, but it’s almost all good fat such as mono-unsaturated fatty acids. Hazelnuts are also a good source of vitamins A and E, as well as arginine, an amino acid that helps relax blood vessels and lower blood pressure. Hazelnut oil is good for the skin, and a popular carrier oil for traditional medicines.
People who are allergic to peanuts, mugwort pollen, Brazil nuts, birch pollen, and macadamia nuts might also be allergic to hazelnuts.