Corylus cornuta subsp. californica

California hazelnut


The Basics

Taxonomy: Kingdom - Plantae (plants). Subkingdom - Tracheobionta (vascular plants). Superdivision - Spermatophyta (seed plants). Division - Magnoliophyta (flowering plants). Class - Magnoliopsida (dicotyledons). Subclass - Hamamelididae. Order - Fagales. Family - Betulaceae (birch). Genus - Corylus L. Species - Corylus cornuta Marshall. Variety - Corylus cornuta subsp. californica (A. de Candolle) E. Murray.

Ecology: California hazelnut may persist into late succession, although it is more common in seral communities. In the Willamette Valley, California hazelnut grows in late-successional Oregon white oak/California hazelnut-poison-oak-Saskatoon serviceberry (Toxicodendron diversilobum - Amelanchier alnifolia) communities where fire has been excluded for 140+ years. California hazelnut may be important in gap succession in mature and old-growth Douglas-fir forests. This subspecies is most common on mesic and/or lightly shaded sites. It is grows on wooded hillsides and streambanks and in coves and canyons. California hazelnut is not as well adapted to cold sites as beaked hazelnut (Corylus cornuta subsp. cornuta). In British Columbia, where California hazelnut is at the edge of its northern range, it occurs only on sheltered sites in the rain shadow of the Coast Ranges.


California hazelnut is a deciduous shrub or small tree with ascending branches. Leaves are thin to leathery, hairy, and have serrated edges. California hazelnut are shrubs or trees , open-spreading, to 8(--15) m; trunks usually several. Bark dark brown to blackish. Branches ascending; twigs sparsely to moderately pubescent, bearing glandular hairs. Winter buds containing inflorescences broadly ovoid, 3--5 3--5 mm, apex acute. Leaves: petiole pubescent, often bearing well-developed glandular hairs. Leaf blade nearly orbiculate or broadly elliptic, 4--7 3.5--7 cm, leathery, base nearly cordate, margins coarsely doubly serrate, apex obtuse to acute, abaxially moderately pubescent, villous to tomentose on major veins and in vein axils. Inflorescences: staminate catkins usually in clusters of 2--3, 4--6 0.5--0.8 cm; peduncles mostly 5--10 mm. Nuts in clusters of 2--4; involucral tubular beak less than 2 times length of nuts, hispid. Root and rhizome system is shallow.


In the WFDP: California hazelnut is subject to herbivory in the WFDP; elk, in particular, may browse California hazelnut to a fatal extent. Another key factor affecting mortality of California hazelnut in this energy-limited system is suppression. The primary pathogen affecting California hazelnut in the WFDP is Armillaria root rot (aka Honey fungus; Armillaria spp.).

Fire effects: California hazelnut sprouts from the root crown after top-kill by fire. Some easternmost populations may sprout from rhizomes, although their ability to do so after fire had not been well studied. California hazelnut was rated low in relative flammability based on an assessment of scorch damage and fire consumption of shrub crowns.


Seed production and dispersal: The inflorescences are catkins. Male and female catkins develop on separate twigs before leaf emergence.. Male catkins grow laterally on short shoots of branchlets, usually in clusters of 2 to 3. Female catkins are small and ovoid in shape, and clustered at the ends of short branches. The fruit is a stiff, hairy involucre with a long, tubular beak shape. The seeds are unwinged nuts, growing in clusters of 2 to 6. A variety of birds and mammals disperse the nuts. Jays and rodents are most important to successful Corylus cornuta seed dispersal and subsequent seedling establishment. Steller's jays and scrub jays collect and cache California hazelnut seeds. They may disperse nuts over relatively long distances

Vegetative Reproduction: California hazelnut sprouts from the root crown and/or rhizomes after top-kill. It may also layer. Fire, heavy browsing, or mechanical damage promote sprouting. Saplings have few rhizomes; therefore, their ability to sprout is limited.

Species Distribution


USDA Plants Database
USDA, NRCS. 2016. The PLANTS Database. National Plant Data Team, Greensboro, NC 27401-4901 USA.

USFS Plant Database
Habeck, R. J. 1992. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory.

Flora of North America
Flora of North America Editorial Committee, eds. 1993+. Flora of North America North of Mexico. 19+ vols. New York and Oxford.