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Juglans regia

Higher Taxonomy
Family: JuglandaceaeView DescriptionDichotomous Key

Habit: Shrub, tree; monoecious. Leaf: odd-(even-)1-pinnate, alternate, deciduous; stipules 0. Inflorescence: catkin, generally appearing before leaves, 1 or clustered; flowers generally 1 in bract axils. Staminate Inflorescence: pendent, elongate, many-flowered, on last year's twigs. Pistillate Inflorescence: erect; flowers 1--many, at tip of new twigs. Staminate Flower: calyx [0 or] lobes generally 4 [2, 6]; petals 0; stamens 3--40[50]; pistil 0 or vestigial. Pistillate Flower: calyx [0] or lobes 4; petals 0; stamens 0; ovary 1, inferior, chamber 1 above, generally 2 below, styles 2, plumose. Fruit: nut enclosed in husk or winged nutlets.
Genera In Family: 9 genera, > 60 species: northern temperate, subtropical mountains; some ornamental, cultivated for wood, nuts (Carya hickory, pecan; Juglans walnut). Note: In Carya, Juglans, husk included in fruit diam, even though derived from involucre, calyx, and therefore not technically part of fruit.
eFlora Treatment Author: Alan T. Whittemore
Scientific Editor: Thomas J. Rosatti.
Genus: JuglansView DescriptionDichotomous Key

Common Name: WALNUT
Stem: bark smooth to furrowed in age, gray to gray-brown; twig centers chambered; buds scaly. Pistillate Inflorescence: flowers 1--few; in fruit erect. Pistillate Flower: styles elongate. Fruit: 1--3 unwinged nuts per inflorescence; leathery husk enclosing, not separating from each nut, not splitting.
Species In Genus: 21 species: North America, temperate Asia, South America. Etymology: (Latin: Jove's nut) Note: Wood used for interior finishing, furniture; source of nuts, dye. Juglans nigra L., occasionally planted, resembles Juglans hindsii but has leaflets uniformly pubescent abaxially, nuts deeply grooved, coarsely warty.

Juglans regia L.
Stem: Trunk 5--30 m. Leaf: petiole 5.5--11 cm; leaflets 5--11, 10--22 cm, elliptic to oblong-ovate, entire, generally short-acuminate (less often acute), abaxial vein axils with tufts of hairs. Fruit: 3.5--5 cm diam, nut shell +- thin, wrinkled.
Ecology: Seedlings occasionally near cultivated trees; Elevation: < 200 m. Bioregional Distribution: n NCoRO, GV, CW, SW; Distribution Outside California: native to southwestern Asia. Flowering Time: Apr Note: Widely cultivated for nuts. Very short-lived in California unless grafted on resistant roots of Juglans hindsii or Juglans hindsii × Juglans regia, the latter reproducing in wild vegetation near plantings. Juglans regia also crosses with Juglans californica where planted near stands of the latter sp. Further study of walnut hybrids in California needed.
eFlora Treatment Author: Alan T. Whittemore
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Citation for this treatment: Alan T. Whittemore 2016. Juglans regia, in Jepson Flora Project (eds.) Jepson eFlora,, accessed on October 23, 2016.

Citation for the whole project: Jepson Flora Project (eds.) 2016. Jepson eFlora,, accessed on October 23, 2016.

Geographic subdivisions for Juglans regia:
n NCoRO, GV, CW, SW;
Markers link to CCH specimen records. Yellow markers indicate records that may provide evidence for eFlora range revision or may have georeferencing or identification issues. Purple markers indicate specimens collected from a garden, greenhouse, or other non-wild location.
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.