The American Hazelnut

The nut that fed a continent

If the oak was the nut that made societies possible across the globe, the hazelnut allowed humans to survive before it could thrive. Quickly growing with loads of nuts after only a few years, the simple hazelnut is likely the most important wild food crop in human history. Today, hazelnut exists on the periphery— hazelnut coffee, Nutella, and so on— hazelnut is a flavor that speaks to us collectively and ancestrally. The American hazelnuts, however, are not the hazelnuts you’re likely familiar with. The hazelnuts that do manage to find their way into our diets are predominantly European hazelnuts, as their nuts are larger and easier to process, due to 5,000 years of domestication.¹ American hazelnuts, however, remain important in the production of commercial hazelnuts because of their resistance to Eastern Filbert Blight.

Before we can dive into its potential today, we need to back up. It’s surprising to discover the hazelnut actually belongs to the birch family, it seems obvious when you notice the separate male pollen catkins and female flowers on the same bush. A fast-growing, early succession family, hazelnuts were one of the first protein-producing trees to work their way toward the polar caps after the last ice age, and humans followed them. The American hazelnut, Corylus americana, can be found in savanna thickets, on the edges of forests, and sprouting occasionally in prairies. Because of indigenous land stewardship, the native hazelnut was once a dominant species in our ecosystems across the entire continent, and there’s evidence of human interaction for at least 7,000 years on the continent, but due to land management changes, the hazelnut is facing functional extinction due to population decline.²,³ This might seem surprising, given the wide range of soil and water needs that the American Hazelnut can handle. Shrublike, they grow in dry, sandy soils but can also be found along the edges of wetlands, and anywhere in between. These bushes can be found in part shade and full sun, the only significant difference being the nut productivity between these two sites.

While the American Hazelnut is considered to be smaller and by proxy low-productivity compared to the European hazelnut, its importance for our local ecology has yet to get the memo— at least 131 species of caterpillars are supported by the American Hazelnut, alongside a number of birds, such as the bluejay.⁴ Historically, the American Hazelnut took over poor, disturbed sites, while today those same sites are overrun by invasive species, particularly nitrogen-fixing species like Autumn Olive, Black Locust, and Tree of Heaven.⁵ Between suburbanization (and the corresponding habitat loss), land stewardship changes, and invasive species pressure, the American Hazelnut has an uphill battle to remain on the American landscape.

Despite all of these challenges, the American Hazelnut still has so much to offer and is a worthy plant to consider utilizing for future food systems. Hazelnuts produce nuts within a few short years and have been estimated to produce up to 200 pounds of nuts per acre in a wild setting, while also producing protein-heavy crops as early as August. In fact, American hazelnut’s caloric composition is 25.81% crude protein, higher than black walnuts (around 15%), acorns (5%), pecans (17%), and hickories (17%).⁶ While we often consider caloric production to be the easiest tool to measure the importance of a crop, protein, calorie for calorie, is the most important for long-term sustainability on the landscape.

This puts hazelnuts in a similar productivity range to black walnuts while also being a small shrub that occupies an entirely different niche while also producing calories with a much quicker turnaround from planting (again, two to five years for productivity to fully ramp up versus potentially two decades)! It also puts hazelnuts at a similar caloric profile per hour of labor of white oaks!⁷

Unlike hickories, hazelnuts aren’t a good option for boiling, but in terms of non-boiled nut options, hazelnuts make up for their small size with easy shells and lack of need for leaching like acorns. The biggest challenge in harvesting the hazelnut is twofold; they’re a preferred species of many animals in the ecosystem, meaning we cannot wait until they fall to the ground, and this leads to the second problem, which is finding the nuts on the tree as their husks are green as their leaves, making identification slow. When nuts hold onto the trees after the leaves fall, harvesting is more quick and they are often more easily husked later in the year. This makes such a significant difference, that the figure above of 592 calories per hour jumps to over 4,000 calories per hour when harvesting can be done in late October. This suggests that breeding work shouldn’t just be focused on larger hazelnuts but also on later harvesting periods.

Historically, humans were cracking hazelnuts on a stone with a pit or with a wooden mortar and pestle, and indigenous people in North America have done so for at least 12,000 years.⁸ However, it’s worth noting that from the end of the last ice age until fairly recently, hazelnuts were the universal crop across the temperate globe— the hazelnut was not unique to North America, but that doesn’t make our native hazelnuts any less special.

Indigenous people— from the Ireland to the Pacific coast— often harvested hazelnuts from squirrel caches or would bury inedible hazelnuts away from the tree to draw the squirrels away.⁹ In fact, squirrels are so ingrained in hazelnut harvesting, in Sm’algyax, the Ts’msyen language, the term for hazelnut literally means “food of the squirrel”— winneeym desx.¹⁰ Much like the Ozark chinquapin, Sand Hickory, and potentially even the Bur Oak, there’s evidence that select hazelnuts (in this case, Beaked hazelnuts, which are more common on the western half of the continent) were identified and moved across the continent, as evidenced by disjunct populations found in British Columbia.

These locations are also home to several archaeological sites with remains of charred hazelnut fragments, processing pits, and other tools for storage, grinding, and hammering. and Indigenous communities still live in these areas. In the Pacific Northwest, the beaked hazelnut, a close relative of the American hazelnut, is often found in thickets alongside the Pacific crabapple; so much so that these plants being found together are considered indicators of indigenous village sites.¹¹ In the Midwest and the East Coast, hazelnut is often found around elderberry and can often reflect the edges of historical burning patterns, often guided by landscape changes.¹²

Further, a disjunct population of American hazelnut was discovered only last year in the Ottawa District. This population hasn’t been assessed for distinct markers to suggest where it came from, but remains substantially separate from other American hazelnuts and evidence suggests they had been managed by the indigenous inhabitants prior to colonization.¹³

Earlier we mentioned Eastern Filbert Blight attacking European hazelnuts. This disease is caused by the fungus Anisogramma anomala and leads to the death of European hazelnuts within 5-12 years, while only causing small cankers on C. americana (American hazelnut).¹⁴ Backbreeding C. americana into European hazelnuts has been an ongoing project for breeders in North America, although progress has been slow and not enough folks have invested in this breeding. Of the nearly 200 cultivars of hazelnuts used for commercial production, only two of any importance have been American— Rush & Winkler.¹⁵

However, Dr. Thomas Molnar at Rutgers is working hard to take advantage of the unique genetics of the American hazelnut— they’ve collected hazelnuts from across the country to develop a nursery of 1899 seedlings from 128 seed lots to catalog the genetic diversity of the American hazelnut.¹⁶ He believes that this will provide the framework for future breeding projects between American & European hazelnuts.

This doesn’t mean that the only value for American hazelnut is specifically because of its genetics to give other species its resistance. Despite limited interest outside of Rutgers, C. americana shows great promise as an oilseed crop, with good cold hardiness to survive where European hazelnuts struggle and oil that is comparable to European hazelnuts, despite the lack of breeding and selection work. Hazelnut oil is high in oleic acid, higher than most other vegetable oils, and is similar to olive oil in this sense.¹⁷

Research assessing hazelnuts for oil production, however, has pointed to a different direction in terms of breeding selection; increasing clusters per square meter. Regardless of the size of the nuts on the bushes, 79% of the oil production variance was accounted for simply by the cluster density.¹⁸ While hazelnut oil has been recognized as a luxury cooking oil, it also works as an effective engine lubricant.¹⁹ Ultimately, what this means is that breeding projects for hazelnuts should have different focuses depending on the product; hazels for easy— late— harvest, and hazelnuts with high nut cluster densities.

While this article has been focused on the American hazelnut, it isn’t the only hazelnut native to North America—the beaked hazelnut is also common in North America, as well as others with smaller footprints on the landscape. In reality, there’s very little written on the American hazelnut at all, and little has been done to identify potential cultivars around hazelnuts. That doesn’t mean we’re not working on it, though.

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1. Bassil, N. V., Botta, R., and Mehlenbacher, S. A. (2005). Microsatellite markers in hazelnut: Isolation, characterization, and cross-species amplification. Journal of American Horticultural Science 130(4): 543–549.

2. https://www.facebook.com/Indigenouslandscapes/posts/pfbid02zMjeT5jGiHVbwX25gM4XJVMcNtC6sXCJyD2sGJAoKGr9nqFpw8mD8gQvSfAxKB1il

3. Leopold EB, Boyd R. 1999. An Ecological History of Old Prairie Areas in Southwestern Washington. Pages 139–163 in Boyd R eds. Indians, Fire and the Land in the Pacific Northwest. Oregon State University Press.

4. https://mainenativeplants.org/wp-content/uploads/2020/04/AmericanHazelnut.pdf

5. Munson, P. J. (1984). Experiments and observations on Aboriginal Wild Plant Food Utilization in eastern North America. Indiana Historical Society.

6. Wainio, Walter W.; Forbes, E.B. 1941. “The chemical composition of forest fruits and nuts from Pennsylvania”. Journal of Agricultural Research. 62 (10): 627-635.

7. https://poorprolesalmanac. substack.com/p/oaks-and-acorns

8. Comberti, C., Thornton, T. F., de Echeverria, V. W., and Patterson, T. (2015). Ecosystem services or services to ecosystems? Valuing cultivation and reciprocal relationships between humans and ecosystems. Global Environmental Change 34: 247–262.

9. Armstrong, C. G., Dixon, W. M., & Turner, N. J. (2018). Management and traditional production of beaked hazelnut (K’áp’xw-az’, Corylus cornuta; Betulaceae) in British Columbia. Human Ecology, 46(4), 547–559. https://doi.org/10.1007/s10745-018-0015-x

10. Turner NJ. 2014. Ancient Pathways, Ancestral Knowledge: Ethnobotany and Ecological Wisdom of Indigenous Peoples of Northwestern North America. McGill-Queen’s University Press.

11. McDonald J. 2005. Cultivating in the Northwest: Early Accounts of Tsimshian Horticulture. Pages 240–271 in Deur D, Turner NJ eds. Keeping it Living: Traditions of Plant Use and Cultivation on the Northwest Coast of North America. University of Washington Press.

12. https://lovenativeplants.com/blog/elderberry

13. Mueller, J., Clarkin, O., & Bélair, A. (2022). A disjunct population of American hazelnut (corylus americana): A new plant species for the Ottawa District. The Canadian Field-Naturalist, 136(2), 156–161. https://doi.org/10.22621/cfn.v136i2.2863

14. Sathuvalli VR, Chen H, Mehlenbacher SA, Smith DC. 2011. DNA markers linked to eastern filbert blight resistance in BRatoli^ hazelnut (Corylus avellana L.). Tree Genetics & Genomes (2):337–345.

15. Sathuvalli VR, Mehlenbacher SA (2012) Characterization of American hazelnut (Corylus americana) accessions and Corylus americana 9 Corylus avellana hybrids using microsatellite markers. Genet Resour Crop Evol 59:1055–1075

16. Molnar, T. J., Honig, J. A., Mayberry, A., Revord, R. S., Lovell, S. T., Mehlenbacher, S. A., & Capik, J. M. (2018). corylus americana: A valuable genetic resource for developing hazelnuts adapted to the eastern United States. Acta Horticulturae, (1226), 115–122. https://doi.org/10.17660/actahortic.2018.1226.16

17. Torres MM, Martı´nez ML, Maestri DM (2005) A multivariate study of the relationship between fatty acids and volatile flavor components in olive and walnut oils. J Am Oil Chem Soc 82:105–110

18. Demchik, M., Fischbach, J., Kern, A., Lane, J., McCown, B., Zeldin, E., & Turnquist, K. (2014). Selection of American hazelnut as a potential oilseed crop. Agroforestry Systems, 88(3), 449–459. https://doi.org/10.1007/s10457-014-9704-7

19. KEVEN, A., & ÖNER, C. (2023). Emission and lubrication performance of hazelnut oil as a lubricant. International Journal of Computational and Experimental Science and Engineering. https://doi.org/10.22399/ijcesen.1321604