Corylus cornuta Marsh.

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Credits

Owen Johnson & Richard Moore (2023)

Recommended citation
Johnson, O. & Moore, R. (2023), 'Corylus cornuta' from the website Trees and Shrubs Online (treesandshrubsonline.org/articles/corylus/corylus-cornuta/). Accessed 2024-05-25.

Genus

Common Names

  • Beaked Hazel

Synonyms

  • Corylus rostrata Ait.
  • Corylus mexicana K. Koch
  • Corylus cornuta var. megaphylla Victorin & J. Rousseau

Glossary

apex
(pl. apices) Tip. apical At the apex.
nut
Dry indehiscent single-seeded fruit with woody outer wall.
subspecies
(subsp.) Taxonomic rank for a group of organisms showing the principal characters of a species but with significant definable morphological differentiation. A subspecies occurs in populations that can occupy a distinct geographical range or habitat.

Credits

Owen Johnson & Richard Moore (2023)

Recommended citation
Johnson, O. & Moore, R. (2023), 'Corylus cornuta' from the website Trees and Shrubs Online (treesandshrubsonline.org/articles/corylus/corylus-cornuta/). Accessed 2024-05-25.

A suckering, thicket-forming shrub to 3(–5) m. Bark pale brown, smooth. Young twigs sometimes glabrous or with sparse non-glandular hairs. Leaf 4–12 × 3–9 cm, ovate to narrowly elliptic, doubly serrated and sometimes slightly lobulate around the shoulders, narrowly cordate to rounded at the base, apex acuminate, pubescence sometimes confined to axillary tufts and to the veins below the leaf; petiole 8–12 mm long, glabrous to moderately pubescent, the hairs with (subsp. californica) or without glands (subsp. cornuta). Male catkins usually 2–3 together, 4–6 cm long; peduncles usually only 1–2 mm long. Nuts in clusters of 2–6, small (c. 12 mm long), thick shelled, completely wrapped in a smooth husk whose apex is constricted to form a narrow beak 2–3(–4) times longer than the nut, not deeply toothed; husk with dense, stiff, penetrating hairs. Flowering February–March (in situ); fruit ripening early (August). (Furlow 1997; Bean 1981).

Distribution  Canada Alberta, British Columbia, Manitoba, New Brunswick, Newfoundland, Nova Scotia, Ontario, Prince Edward Island, Quebec, Saskatchewan. France St Pierre and Miquelon. United States Alabama, Colorado, Connecticut, Georgia, Idaho, Illinois, Iowa, Kentucky, Maine, Maryland, Massachusetts, Michigan, Minnesota, Montana, New Hampshire, New Jersey, New York, North Carolina, North Dakota, Ohio, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Vermont, Virginia, Washington, West Virginia, Wisconsin, Wyoming.

Habitat Wood margins, open woodland, thickets, waste ground.

USDA Hardiness Zone 3

RHS Hardiness Rating H7

Conservation status Least concern (LC)

The Beaked Hazel is one of two species native to temperate North America. It has a wider range than C. americana, reaching the west coast as subsp. californica. (The above description refers to subsp. cornuta; though this is the ‘eastern’ subspecies, its range extends to eastern Washington State and south-eastern British Columbia.) Compared to C. americana, Corylus cornuta subsp. cornuta is a smaller plant whose suckering habit is much more pronouced; it is less of a woodlander, though its dense thickets can become a nuisance in well-managed forests (Furlow 1997). It is the hardier species, and it roots more deeply, allowing it to survive forest fires and summer drought (Molnar 2011). It dislikes waterlogged conditions and heavy clay soils (Missouri Botanical Garden 2023). It is usually very resistant to Eastern Filbert Blight, as it can sometimes grow alongside the host species, C. americana (Molnar 2011). Its fruits are distinctive: the husk has evolved into a protective sheath whose fine sharp bristles continue to protect the nut from small mammals even after it has fallen off the bush. The curiously elongated apex of the sheath has given the species its name (cornuta: horned) – although observers are more likely to be reminded of the trunk of a tiny elephant. In subsp. cornuta the ‘horn’ is 2–3 times the length of the nut. The nut itself is tasty, as in all hazels, but is small and thick-shelled. Out of fruit, the absence of long, gland-tipped hairs is a useful feature differentiating subsp. cornuta from C. americana (and from subsp. californica).

Native Americans found many herbal uses for this plant (Furlow 1997), but as an untidily suckering shrub with inferior fruit Corylus cornuta has been very little used in hazelnut production, while its abundance in the wild and its lack of particular ornamental qualities have both stood against its use in gardens of any sort. This, in turn, is presumably a contributory factor behind the absence, as yet, of any worthwhile ornamental selections.

The Third Duke of Argyll first cultivated Corylus cornuta in England in 1745 (Bean 1981). The Royal Botanic Garden Edinburgh grows plants collected in Michigan in 1986 and in North Carolina in 2011 (Royal Botanic Garden Edinburgh 2023), while in light shade and in the warmer summers of Berkshire, a group planted in the Valley Gardens at Windsor among pampered and irrigated rhododendrons has grown to seven metres tall – a stature typical only of the western subsp. californica (Tree Register 2023).


subsp. californica (A.DC.) A.E.Murray

Common Names
Californian Hazel

Synonyms
Corylus rostrata var. californica A. DC
Corylus cornuta var. californica (A. DC.) Sharp
Corylus californica (A. DC) Rose
Corylus rostrata var. tracyi Jepson
Corylus cornuta var. glandulosa B. Boivin

A shrub or small tree to 8(–15) m, usually with several trunks and a suckering habit. Bark dark brown to blackish. Young twigs sparsely to moderately pubescent, with some longer, glandular hairs. Leaves nearly orbicular to broad-elliptic, 4–7 × 3–7 cm, base rounded to cordate, tip obtuse to acute, margin coarsely double-serrate, both surfaces pubescent; petiole pubescent and often with longer, glandular hairs. Male catkins with peduncles usually 5–10 mm long. Nuts in clusters of 2–4, the husk forming a beak which is less than twice as long as the nut itself. (Furlow 1997).

Distribution

  • Canada – Coastal British Columbia.
  • United States – Coastal Oregon, Washington, and northern coastal California.

RHS Hardiness Rating: H6

USDA Hardiness Zone: 6

Corylus cornuta subsp. californica differs in enough ways from subsp. cornuta, the form which grows across large parts of North America, for many authorities to consider it a species in its own right (C. californica (A. DC) Rose). Phylogenetic analyses have failed to indicate that the two forms are sufficiently close, or distant, to decide this subject, and this account follows Plants of the World Online in maintaining the traditional subspecific rank (Royal Botanic Gardens, Kew 2023). It is sometimes suggested that the range of the two forms can overlap in central Washington and British Columbia and that hybrids can occur here (Bressette 2023). ‘Californian Hazel’ is a slight misnomer: the plant’s centre of distribution lies further north and it is certainly not a feature of the Mediterranean climate of southern California.

Physically, California Hazel differs from subsp. cornuta in its larger stature, as a multi-stemmed small tree rather than a densely-suckering shrub, its glandular and more pubescent twigs and leaf-stalks, its broadly ovate leaves which lack the deeply heart-shaped base and sudden sharp tip of most hazels’, and the husks of its nuts, whose distinctive ‘beak’ is typically less than twice the length of the nut itself. Ecologically, it prefers wetter, shadier sites. The greater stature, at least, is a feature commonly found among plants adapted to the kinder growing conditions of the Pacific Northwest; a comparable case can be observed in the western subsp. laevigatus of the snowberry Symphoricarpus albus.

Under whatever name, Californian Hazel may never have been used in the breeding of commercial hazelnuts, and is hardly seen in gardens. It shows good resistant to Eastern Filbert Blight (EFB) (Molnar 2011), even though EFB is not a native pathogen near the west coast, and it is also hardy enough to grow at Arboretum Norr in Sweden (‘the most northerly arboretum in the world’; Arboretum Norr 2023). Two bushes accessioned in 2007 are cultivated at the Sir Harold Hillier Gardens in England, while in the more continental climate of North Carolina it is a feature of the arboretum of the Bartlett Tree Research Laboratories (Royal Botanic Garden Edinburgh 2023).