Hazelnuts
Hazelnuts, also known locally as filberts, are the nuts of various species of hazels, which are widely distributed throughout temperate climates in the Northern Hemisphere. Hazels are in the Betulaceae family, along with birches and alders. Most are shrubs, but some species grow into trees.
The Corylus genus originated in eastern Asia, from where it spread from eastern Russia to North America, and in the opposite direction to western Asia and Europe.
There are roughly 15 species of hazelnuts in the world (depending on the authority). With the wide variety of ecosystems found in our region, most of these could be successfully grown here. Locally, we have a native species, the western beaked hazel, Corylus cornuta ssp. california. However, the species grown commercially in Oregon’s orchards is the European hazel, Corylus avellana.
The state of Oregon, and the Willamette Valley, specifically, produces at least 99% of the United States’ hazelnut crop. The US (Oregon, really) is a leading hazelnut producer globally, after Turkey and Italy, although Turkey outpaces both significantly, producing 60-70% of the global harvest.
Cooking with hazelnuts
Hazel trees bloom in winter and produce nuts in late summer and early fall.
All species of hazelnuts are edible. Though they are edible raw, they are usually roasted to bring out their full flavor. Hazelnuts are used especially in baking, in pastries, cakes, and tarts.
Hazelnut liqueur: the most famous brand is Frangelico, produced in Italy, but hazelnut liqueurs are common and traditional anywhere in Europe the plants are found.
Hazelnut oil: hazelnut oil is aromatic and best used in low-temperature applications such as salad dressings.
Hazelnut spread: roasted hazelnuts are ground into a paste. Often this is combined with chocolate, as with the famous brand Nutella.
Species
Hazelnuts
European hazel (Corylus avellana)
‘Barcelona’
Asian hazel (Corylus heterophylla)
American hazel (Corylus americana)
Beaked hazels
American beaked hazel (Corylus cornuta)
Asian beaked hazel (Corylus sieboldiana)
Tree hazels
Turkish tree hazel (Corylus colurna)
Indian hazel (Corylus jacquemontii)
European hazels
Corylus avellana, the European hazel, is the species of hazel planted in commercial hazelnut orchards in Oregon. European hazels are thought to have been first introduced to our region by early French settlers.
The European hazel is distributed in the wild across most of Europe and West Asia. From recent genetic research, it appears to have been domesticated independentally in Turkey, Iran, and the Mediterranean. They have been cultivated in Europe since at least the Roman period.
The variety planted most commonly in the Pacific Northwest is ‘Barcelona’, which traces its origins to Spain. The oldest orchard in Oregon, Dorris Ranch, was established in 1903 near Eugene with two hundred of these hazel trees.
Corylus maxima, a type of hazelnut with a long involucre, is typically considered a separate species from Coryulus avellana, but this classification is currently heavily disputed. Research so far points to C. maxima most likely being a variety of cultivated C. avellana rather than a distinct species.
Involucres
The various species of hazel trees can be can be characterized according to the type of husk that surrounds their nuts. This husk, or “involucre”, is either short, long, or spiny. C. avellana produces clusters of nuts with short involucres.
Beaked hazels
The American beaked hazel, Corylus cornuta, is distributed throughout temperate North America, generally in more northern areas but also found at lower latitudes in mountainous regions such as the Sierra Nevada or Appalachian Mountains.
The species is divided into two subspecies, the western beaked hazel, Corylus cornuta ssp. california, and the eastern beaked hazel, Corylus cornuta ssp. cornuta. These are often listed as varieties rather than subspecies, but it seems more appropriate that these be considered subspecies due to their geographical separation. The eastern beaked hazel occurs only in the eastern US and Canada, whereas the western beaked hazel is found along the west coast, from Alaska down to northern California.
The moniker “beaked hazel” comes from the long involucre that covers the nuts. The nut is on par with the European hazelnut in terms of quality and culinary use, and was a staple food for indigenous people. The beaked hazel does produces lower yields than the European hazel, but as a native species, it is completely adapted to our climate and does not suffer from many diseases. As a result, it has been used to produce hybrids with the European hazel.
The Asian beaked hazel (Corylus sieboldiana) of northern China, Korea, and Japan is the closest Asian relative to the beaked hazel of North America and the likely ancestor of the American species. It is highly similar to the American beaked hazel.
Other hazel species
The species listed below are those that native to North America or species that are consumed in other parts of the world.
These are generally of less interest than the European hazel and the American beaked hazel but have cultural significance or could have niche use (colder micro-climates, etc.).
The Asian hazel (Corylus heterophylla) is highly similar to the European hazel, but more cold-hardy. It is commercially cultivated in China, Korea, and Japan and although it’s fairly unknown in Europe and North America, it’s the second-most cultivated species in the world after C. avelllana. Breeding programmes have been undertaken in China between the two species and the resulting hybrids have been planted as well.
Corylus americana, the American hazel, is a species native to eastern North American. With a short involucre, it is similar to C. avellana but produces a slightly smaller nut and is not commonly cultivated.
The Turkish tree hazel (Corylus colurna) is the largest species of hazel, forming a full-sized tree. It is distributed from the Balkans and Turkey into western Asia and the western Himalayan Mountains. The nuts, which have a spiny involucre, of the Turkish hazel are smaller and have harder shells than those from C. avellana, but are collected for consumption in Turkey and northern India. The trees are planted in some European cities as a street tree, but are fairly rare in the Pacific Northwest.
The Indian hazel (Corylus jacquemontii) is very similar to C. colurna, but the tree is smaller and produces fewer nuts per cluster. It ranges from western Asia to the western Himalayas, where it is collected and consumed by local populations.
