Corylus avellana

Species evidence

Record the organs supporting identification and the alternatives they exclude.

1. What do mature husk enclosure, husk lobing and nut dimensions indicate about C. avellana versus C. maxima or C. colurna? definition
2. Which diagnostic organs were observed on this plant, when, and in which photographs or specimens? provenance
3. What missing or conflicting character requires identification to remain provisional? boundary

Cultivar attribution

Retain traceable identity claims without treating a commercial name as proof.

1. Which supplier, accession or mother-plant record supports the cultivar and species attribution? provenance
2. Does unusual foliage, branch form or fruit morphology fit a documented cultivar, or require review of the identification? boundary

Stool membership

Record what evidence joins stems into one observed plant.

1. Which stems share an observed basal stool, and which nearby shoots have unverified connections? boundary
2. For a grafted specimen, which observed shoots arise above or below the graft union? measurement

Regrowth capacity

Assess the stool through dated cutting history and observed recovery.

1. When was the stool last cut, and what records distinguish stool history from current stem age? provenance
2. How many live replacement shoots developed, and how have their length and basal diameter changed? measurement
3. Does observed recovery support another cut for the stated objective, or favour retaining stems and reassessing? action

Pollen opportunity

Evaluate whether suitable pollen could reach receptive flowers.

1. On which dates were pollen shedding and female receptivity observed or assessed separately? measurement
2. Which nearby hazels have documented compatibility and overlapping pollen release? provenance
3. What additional observation is needed before attributing poor nut set to inadequate pollination? action

Crop outcome

Use dated samples to explain the difference between visible nuts and harvestable output.

1. What proportions of a defined sample are developing, filled, empty or visibly damaged? measurement
2. What observations distinguish failure to develop from premature drop or animal removal? measurement
3. Which locally validated maturity indicators support harvest for the intended use? action

Site fit

Record measured conditions and locally relevant performance evidence.

1. What root-zone moisture, drainage, pH and crown light measurements accompany the current growth assessment? measurement
2. Did frost or dry conditions coincide with this plant's recorded flowering or nut-development stages? measurement
3. Which site adjustment is supported for this hazel's stated objective and observed limitation? action

Condition assessment

Locate and track abnormal buds, foliage, stems and nuts before selecting a response.

1. How extensive are enlarged buds, leaf coatings, shoot dieback, bark injury or nut holes, and how have they changed? measurement
2. What diagnostic evidence supports a pest, pathogen or environmental cause rather than a symptom-only label? provenance
3. Should the agent monitor, obtain a diagnostic sample or refer to a locally applicable treatment model? action

Offspring identity

Choose propagation according to whether seedling variation or preservation of an attributed cultivar is intended.

1. Must the new plant preserve a documented cultivar, or is a seedling of recorded parentage acceptable? definition
2. What mother-plant and shoot-origin evidence supports the identity of the selected propagation material? provenance
3. What observed rooting and establishment criteria must be met before separating or transplanting vegetative material? action

Management decision

Make the intended benefit and follow-up assessment explicit before altering the hazel.

1. Is this plant being managed primarily for nuts, coppice stems, ornament, habitat or a documented combination? definition
2. What observed habitat use and linked permissions constrain pruning, coppicing or nut collection at this location? boundary
3. Which intervention is supported now, and what subsequent regrowth, flowering or crop observation will determine whether it succeeded? action

Kinds and varieties

Reported by the breadth pass; each item needs checking against its source before it becomes normative.

• Wild multi-stemmed coppice and hedgerow hazel
• English cobnuts (Kentish Cob and related garden/orchard clones)
• Italian round-kernel groups (Tonda Gentile delle Langhe, Tonda di Giffoni, Tonda Romana)
• Turkish Black Sea landraces (Tombul, Palaz, Çakıldak and related fındık types)
• Pacific Northwest orchard cultivars (Barcelona and later Oregon releases, some with hybrid ancestry)
• Corkscrew/contorted hazel (C. avellana 'Contorta')
• Purple- and gold-leaved ornamentals ('Fuscorubra', 'Purpurea', 'Aurea', 'Red Majestic')
• Long-husk "filbert" market types (often C. maxima or avellana-maxima hybrids rather than pure C. avellana)

1. Which of these kinds and varieties hold for the sense of Corylus avellana this model covers, and on what evidence? provenance

Identifiers and schemes

Reported by the breadth pass; each item needs checking against its source before it becomes normative.

• Wikidata - Q10986 - Item for the species Corylus avellana.
• Botanical name (ICN) - Corylus avellana L. - Published in Species Plantarum 2: 998 (1753); type species of Corylus.
• IPNI - 295513-1 - Standard IPNI record for the Linnaean name.
• EPPO Code - CYLAV - Plant-health and pest-reporting code for the species.
• USDA PLANTS symbol - COAV - United States plants-database symbol.
• NCBI Taxonomy - 13489 - NCBI taxon identifier for Corylus avellana.
• Harmonized System (nuts, not the living plant) - 0802.21 (inshell); 0802.22 (shelled) - HS headings for hazelnuts or filberts (Corylus spp.), the usual trade codes for the crop.
• WHO/IUIS allergen nomenclature - Cor a 1, Cor a 8, Cor a 9, Cor a 14 (and related Cor a proteins) - Named hazelnut allergens used in clinical and labelling practice.

1. Which of these identifiers and schemes hold for the sense of Corylus avellana this model covers, and on what evidence? provenance

Standards and regulation

Reported by the breadth pass; each item needs checking against its source before it becomes normative.

• UNECE Standard DDP-03 (Inshell Hazelnuts) - United Nations Economic Commission for Europe
• UNECE Standard DDP-04 (Hazelnut Kernels) - United Nations Economic Commission for Europe
• Codex Standard for Inshell Hazelnuts (CXS 182-1993) - FAO/WHO Codex Alimentarius Commission
• Regulation (EU) No 1169/2011, Annex II (hazelnut as a listed allergen) - European Union
• Council Directive 1999/105/EC on the marketing of forest reproductive material (hazel as a listed tree species in several member states) - European Union
• United States Standards for Grades of Filberts/Hazelnuts in the Shell - USDA Agricultural Marketing Service
• 7 CFR Part 982 (hazelnuts grown in Oregon and Washington) - United States Department of Agriculture
• Protected names such as Nocciola del Piemonte PGI, Nocciola di Giffoni PGI and Nocciola Romana PDO - EU geographical-indication scheme

1. Which of these standards and regulation hold for the sense of Corylus avellana this model covers, and on what evidence? provenance

Real-world use

Reported by the breadth pass; each item needs checking against its source before it becomes normative.

• Commercial orchard nut crop, with Turkey's Black Sea belt supplying most world volume and substantial industries in Italy, Azerbaijan, Georgia, Spain and Oregon, USA.
• Kernel use in confectionery and spreads (gianduja, praline, nougat, chocolate-hazelnut pastes), snack nuts, cold-pressed oil and bakers' flour.
• Traditional coppice product in Britain and western Europe: hurdles, thatching spars, bean poles, walking sticks, charcoal and hedge laying.
• Hedgerow and woodland shrub providing winter mast for squirrels, jays and mice and structurally important habitat for hazel dormouse.
• Ornamental horticulture, especially the contorted and coloured-leaf clones.
• Planting stock and forest reproductive material for farm woodland and agroforestry rather than high-forest timber.

1. Which of these real-world use hold for the sense of Corylus avellana this model covers, and on what evidence? provenance

Typical measurements

Reported by the breadth pass; each item needs checking against its source before it becomes normative.

• Mature height (shrub or small tree) - 3-8 (occasionally to about 15) - m
• Leaf blade length - 6-12 - cm
• Male catkin length at anthesis - 5-12 - cm
• Kernel mass (commercial types) - 0.8-2.0 - g
• Kernel oil content (dry basis) - 50-70 - %
• Kernel moisture for safe storage (trade limits) - ≤6-7 - % wet basis
• Shelling-out (kernel as fraction of inshell nut) - 40-50 - %
• Somatic chromosome number - 2n = 22 - count

1. Which of these typical measurements hold for the sense of Corylus avellana this model covers, and on what evidence? provenance

Failure modes and hazards

Reported by the breadth pass; each item needs checking against its source before it becomes normative.

• Eastern filbert blight (Anisogramma anomala): cankers that kill susceptible orchard trees; the main breeding constraint in North America and a quarantine concern for Europe.
• Big-bud mite (Phytoptus/Phytocoptella avellanae) destroying vegetative and flowering buds.
• Hazelnut weevil (Curculio nucum) and other nut borers causing blank or maggoty kernels.
• Bacterial blight (Xanthomonas arboricola pv. corylina) on shoots, buds and nuts, especially in wet nurseries and young orchards.
• Kernel rancidity and storage moulds; aflatoxin risk if moisture and temperature are poorly controlled.
• Severe IgE-mediated food allergy (seed-storage proteins Cor a 9 and Cor a 14) and birch-pollen-related oral allergy (Cor a 1).
• Spring frost on female flowers and wind-pollination failure, producing blank nuts; alternate bearing in orchards.
• Grey-squirrel bark stripping and nut predation in Britain; nut loss to jays and mice in unnetted orchards.
• In coppice, neglected rotation and deer browsing producing stools that fail to yield usable rods.

1. Which of these failure modes and hazards hold for the sense of Corylus avellana this model covers, and on what evidence? provenance

Regional variation

Reported by the breadth pass; each item needs checking against its source before it becomes normative.

• In Britain the wild plant is "hazel"; cultivated orchard nuts are "cobnuts" (especially Kent). "Filbert" is used for long-husk forms, often C. maxima, and the two names are not applied consistently.
• In North America the crop was long sold as "filbert," especially from Oregon; "hazelnut" is now the preferred trade name for the same nuts.
• Italy treats distinct round-kernel landraces as named products (Piedmont, Giffoni, Lazio) under GI rules; Turkey grades Black Sea fındık by district and landrace (Giresun Tombul as the quality type).
• Spanish production centres on Catalonia and the cultivar Negret; US production is concentrated in the Willamette Valley with a cultivar set built around blight resistance.
• Ornamental 'Contorta' is a garden plant worldwide and is rarely part of the nut trade.

1. Which of these regional variation hold for the sense of Corylus avellana this model covers, and on what evidence? provenance

Neighbouring kinds and how to tell them apart

Reported by the breadth pass; each item needs checking against its source before it becomes normative.

• Corylus maxima (filbert) - Involucre tubular, constricted beyond the nut and clearly longer than the nut; C. avellana has a shorter, lobed, cup-like husk about as long as the nut.
• Corylus colurna (Turkish hazel) - Single-trunked tree with corky-ridged bark and nuts in bristly, deeply dissected involucres; C. avellana is multi-stemmed with a softer, lobed husk.
• Corylus americana (American hazel) - Twigs and petioles glandular-hairy and nuts smaller; confirm with glandular pubescence and native North American range rather than husk shape alone.
• Corylus cornuta (beaked hazel) - Involucre fused into a long, narrow beak well beyond the nut; C. avellana husks are open-lobed, not beaked.
• Carpinus betulus (hornbeam) - Similar plicate, doubly serrate leaves, but fruit is a small nutlet with a three-lobed leafy bract, never a large edible nut in a husk.
• Ostrya species (hop-hornbeams) - Female fruiting structures look like hops (inflated papery bladders), not clustered leafy hazel husks.
• C. avellana × C. americana (and other orchard hybrids) - Morphologically close to C. avellana; separate by pedigree, blight-resistance phenotype and, where needed, molecular markers rather than husk shape.

1. Which of these neighbouring kinds and how to tell them apart hold for the sense of Corylus avellana this model covers, and on what evidence? provenance