Pacific Northwest Plant Profile: California hazelnut (Corylus cornuta var. californica)


Corylus cornuta var. california (leaves)
Flowers in January?
You bet. Although they’re not showy blossoms that attract most people searching for signs of spring, the flowers of California hazelnut are a truly welcome sight in mid-winter to spring. Hazelnuts are monoecious plants, having both soft-yellow male catkins that dangle off the tips of leafless branches, and tiny feathery clusters of red stigmas—decidedly female—that are few and often difficult to see. Due to their timing and structure, they are pollinated by wind, not insects.

Corylus cornuta var. california catkins

California hazelnut is a deciduous, multi-stemmed woodland shrub (or small tree), beautifully textured with soft-green, saw-toothed, velvety leaves that adorn arching branches. In autumn they turn a glowing yellow or gold. Besides seasonal aesthetic interest, there are the hard-shelled edible nuts, which typically mature in late summer to early fall.

A member of the birch family, California hazelnut’s botanical name originates from both Greek and Latin. The genus Corylus comes from the Greek korulos, which means “helmet” and refers to the nearly impenetrable husk on the top of the nut. The epithet, cornuta, means “horned” in Latin and refers to a beaklike point formed by the bracts, or husk, that enclose the developing fruit.

Corylus cornuta var. californica

How it grows
California hazelnut typically can be found on moist, rocky slopes or riparian areas in the understory or at the edge of mixed forests at low to middle elevations.The variety californica naturally occurs in southern B.C., within most counties of Washington and Oregon west of the Cascades (as well as Wallowa County in NE Oregon), and in northern to central California. Another variety,  Corylus cornuta var. cornuta, commonly known as beaked hazelnut, makes its home east of the Cascades and throughout a large portion of the U.S. According to the US Forest Service, although California hazelnut doesn’t naturally grow with other native hazelnut species, “hybridization is possible in the Willamette Valley of Oregon and other locations where it grows adjacent to European filbert (cultivars of C. avellana) orchards.” Corylus americana (American hazelnut) grows in the central and eastern U.S.

Wildlife value
Many wild species eat and disperse the nuts. Rabbits and deer eat leaves and sprouts. Cover is provided for many species of birds, as well as mammals.

Try it at home
California hazelnut doesCorylus cornuta var. california hazelnut well in sun to shade, and prefers moist but well-drained, somewhat acidic soils with a decent amount of organic matter. While  tolerant of clay soils, it doesn’t do well on poorly drained sites. Useful for erosion control on slopes, it will eventually form a thicket. Suckers may be removed in winter (during dormancy) to form more of a treelike habit, but the habitat created by thickets favors many wild animals, especially birds seeking cover, so consider just leaving them to their natural habit.

Mature size varies from 10 feet to 20 feet tall, possibly more with advanced age. Spread is typically 10 to 20 feet, but usually on the low end in garden situations. Since chipmunks, jays and squirrels love the nuts, I suggest you grow as many of these charming shrubs as possible (especially if you want to have the chance to taste them!). Growing more than one shrub also increases pollination, which leads to more nuts per plant. Space them 10 to 20 feet apart (on the low end if you want some density). Though this shrub is quite drought tolerant when established (2 to 5 years), water it deeply but infrequently in the hot summer months thereafter, especially if your site receives a lot of sun or reflected heat.

Squirrel watchingTo grow this plant from seed, collect nuts in late summer or early fall while the husks are still a bit green. Plant them outdoors, an inch or two deep (but make sure a little squirrel isn’t watching you do it!). To make sure they’re viable, place them in a bowl of water for 15 minutes or so, and use only those that sink. Plants can also be ground layered or propagated by semihardwood cuttings in the fall, or suckers may be divided in early spring.

California hazelnut is a good substitute for European hazelnut or English hawthorn.

Grab a partner
Because California hazelnut grows in a variety of plant communities, it gets along well with many other species. Choose partners that would have likely grown in your area. In the Douglas-fir/western hemlock ecoregion, consider red alder (Alnus rubra), vine maple (Acer circinatum), salal (Gaultheria shallon), thimbleberry (Rubus parviflorus), sword fern (Polystichum munitum), deer fern (Blechnum spicant), and woodland strawberry (Frageria virginiana or F. vesca), among others. In the grassland and oak woodland areas of the Willamette Valley, Puget Trough, and Georgia Basin, grow it with Oregon white oak (Quercus garryana), Oregon ash (Fraxinus latifolia), cascara (Rhamnus purshiana), and red-twig dogwood (Cornus sericea), inside-out flower (Vancounveria hexandra) and others. In the southern Coast Range and mountainous areas of southwest Oregon, include tanoak (Lithocarpus densiflorus), madrone (Arbutus menziesii), and serviceberry (Amelanchier alnifolia).

As always, buy plants propagated from source material that originated as close as possible to your site. Using such “local genotypes”  helps ensure that you get plants that are well adapted to your area and preserves genetic diversity that helps plants (and animals) adapt to changing conditions. Ask growers and nurseries about their sources if you’re unsure.

© 2017 Eileen M. Stark

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