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BETULACEAE BIRCH FAMILY

John O. Sawyer, Jr.

Shrub, tree; monoecious. Stem: trunk < 35 m; bark smooth to scaly, peeling in thin layers or not, lenticels present or not. Leaf: simple, alternate, petioled, deciduous; stipules deciduous; blade ovate to elliptic, generally serrate, generally ± doubly so. Inflorescence: catkin, generally appearing before leaves, often clustered; bracts each subtending 2–3 flowers, 3–6 bractlets. Staminate inflorescence: pendent, ± elongate. Pistillate inflorescence: pendent or erect, developing variously in fruit (see key to genera). Staminate flower: sepals 0–4, minute; petals 0; stamens 1–10; pistil vestigial or 0. Pistillate flower: sepals 0–4; petals 0; stamens 0; pistil 1, ovary inferior or superior, chambers 2, each 1-ovuled by abortion, stigmas 2. Fruit: achene, nut, winged or not, subtended or enclosed by 1–2 bracts.
6 genera, 155 species: generally northern hemisphere; some cultivated. [Furlow 1997 FNANM 3:507–538] —Scientific Editor: Thomas J. Rosatti.

Key to Betulaceae

CORYLUS HAZELNUT
Shrub, small tree. Stem: trunk < 6 m; bark smooth or scaly, dark brown; twigs glandular-hairy, becoming glabrous, brown; lenticels small; winter buds ciliate. Leaf: hairy; blade 4–10 cm, oblong to ovate, base oblique-cordate. Staminate inflorescence: 4–7 cm; bracts each subtending 3 flowers, 3 bractlets. Pistillate inflorescence: < 1 cm, appearing as terminal bud; bracts each subtending 2 flowers, 6 bractlets. Staminate flower: sepals 0; stamens 4. Pistillate flower: sepals 4; stigmas showy, red. Fruit: 1–2 per catkin, each enclosed in a papery involucre of 2 fused bracts, not winged.
15 species: northern hemisphere. (Latin: hazelnut, filbert) [Furlow 1997 Syst Bot 26:283–298] Flexible stems used in basket-making; some cultivated as food crop.

C. cornuta Marshall subsp. californica (A. DC.) E. Murray CALIFORNIA HAZEL
NATIVE
Stem: trunks < 4 m. Leaf: petiole 5–10 mm; blade ± velvety-hairy, base cordate, tip acute to acuminate. Fruit: 2–3 cm, involucre vase-shaped.
Common. Many habitats, especially moist, shady places; < 2100 m. Northwestern California, Cascade Range, Sierra Nevada, Central Coast, San Francisco Bay Area; to British Columbia. [Corylus cornuta var. californica (A. DC.) Sharp] Jan–Mar [Online Interchange]

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Citation for the whole project: Jepson Flora Project (eds.) 2013. Jepson eFlora, http://ucjeps.berkeley.edu/IJM.html, accessed on Oct 24 2014
Citation for this treatment: [Author of taxon treatment] 2013. Corylus, in Jepson Flora Project (eds.) Jepson eFlora, http://ucjeps.berkeley.edu/cgi-bin/get_IJM.pl?tid=80489, accessed on Oct 24 2014

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click for enlargement Corylus cornuta subsp. californica
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© 2009 Barry Breckling

Geographic subdivisions indicated for the distribution of Corylus cornuta subsp. californica Markers link to CCH specimen records. If the markers are obscured, reload the page [or change window size and reload]. Yellow markers indicate records that may provide evidence for eFlora range revision or may have georeferencing or identification issues.
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map of distribution 1
(Note: any qualifiers in the taxon distribution description, such as 'northern', 'southern', 'adjacent' etc., are not reflected in the map above, and in some cases indication of a taxon in a subdivision is based on a single collection or author-verified occurence).

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Data provided by the participants of the Consortium of California Herbaria.
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CCH collections by month

Duplicates counted once; synonyms included.
Species do not include records of infraspecific taxa.
Blue line denotes eFlora flowering time.