Editing Juglans (section)

===Taxonomy===
The genus ''Juglans'' is divided into four sections.<ref>Aradhya, M. K., D. Potter, F. Gao, C. J. Simon:  "Molecular phylogeny of ''Juglans'' (Juglandaceae):  a biogeographic perspective",''Tree Genetics & Genomes''(2007)'''3''':363–378</ref>

====Sections and species====
{| class="wikitable"
|-
! Section
! Description
! Image
! Name
! Common Name
! Subspecies
! Distribution
|-
! rowspan="2" style="text-align:center;"| Section ''Cardiocaryon''
| rowspan="2"| Leaves are very large (40–90&nbsp;cm), with 11–19 broad leaflets, softly downy, margins serrated. The wood is soft, and the fruits borne in racemes of up to 20.  The nuts have thick shells. Native to northeast Asia.
|[[File:P4260728.jpg|120px]]
|''[[Juglans ailantifolia|J.&nbsp;ailantifolia]]'' Carr. (''J.&nbsp;cordiformis'' Maxim., ''J.&nbsp;sieboldiana'' Maxim.)
|Japanese walnut
|
*[[heartnut|''J.&nbsp;ailantifolia'' var. ''cordiformis'']] – Heartnut
| Japan and Sakhalin
|-
|[[File:Juglans mandshurica 03.JPG|120px]]
|''[[Juglans mandshurica|J.&nbsp;mandshurica]]'' Maxim. (''J.&nbsp;cathayensis'' Dode, ''J.&nbsp;formosana'' Hayata, ''J.&nbsp;hopeiensis'' Dode, ''J.&nbsp;stenocarpa'' Maxim.)
|Manchurian walnut or Chinese walnut
|
|China, Russian Far East, Korea
|-
! rowspan="2" style="text-align:center;"| Section ''Juglans''
| rowspan="2"|Leaves are large (20–45&nbsp;cm), with 5–9 broad leaflets, hairless, margins entire. The wood is hard. Native to southeast Europe to central Asia.
|[[File:Noix en automne - walnuts.JPG|120px]]
|''[[Juglans regia|J.&nbsp;regia]]'' L. (''J.&nbsp;duclouxiana'' Dode, ''J.&nbsp;fallax'' Dode, ''J.&nbsp;orientis'' Dode)
|common walnut, Persian, English, or Carpathian walnut
|
|Balkans eastward to Himalaya, China
|-
|
|''[[Juglans sigillata|J.&nbsp;sigillata]]'' Dode 
|iron walnut (doubtfully distinct from ''J. regia'')
|
|China
|-
! rowspan="15" style="text-align:center;"| Section ''Rhysocaryon'' (black walnuts)
| rowspan="15"|Leaves are large (20–50&nbsp;cm), with 11–23 slender leaflets, finely pubescent, margins serrated. Native to North America and South America.
|[[File:Juglans australis in Hackfalls Arboretum (2).jpg|120px]]
|''[[Juglans australis|J.&nbsp;australis]]'' Griseb. (''J.&nbsp;brasiliensis'' Dode)
|Argentine walnut, Brazilian walnut
|
| Argentina, Bolivia
|-
|
|''[[Juglans boliviana|J.&nbsp;boliviana]]'' (C. DC.) Dode
|Bolivian walnut, Peruvian walnut
|
| Andes of Bolivia and Peru
|-
|[[File:Juglans californica 2c.JPG|120px]]
|''[[Juglans californica|J.&nbsp;californica]]'' S.Wats.
|California black walnut
|
| California
|-
|[[File:H20130909-9860—Juglans hindsii—Katherine Greenberg (9780612424).jpg|120px]]
|''[[Juglans hindsii|J.&nbsp;hindsii]]'' (Jepson) R.E.Smith              
|Hinds' black walnut 
|
| California
|-
|
|''[[Juglans hirsuta|J.&nbsp;hirsuta]]'' Manning  
|Nuevo León walnut
|
| Mexico
|-
|
|''[[Juglans jamaicensis|J.&nbsp;jamaicensis]]'' C.DC. (''J.&nbsp;insularis'' Griseb.) 
|West Indies walnut
|
| Cuba, the Dominican Republic, Haiti, and Puerto Rico
|-
|[[File:Juglans major foliagenuts.jpg|120px]]
|''[[Juglans major|J.&nbsp;major]]'' (Torrey) Heller (''J.&nbsp;arizonica'' Dode, ''J.&nbsp;elaeopyron'' Dode, ''J.&nbsp;torreyi'' Dode) 
|Arizona black walnut
|
*''J.&nbsp;major'' var. ''glabrata'' Manning
|Mexico, United States
|-
|[[File:Juglans microcarpa kz02.jpg|120px]]
|''[[Juglans microcarpa|J.&nbsp;microcarpa]]'' Berlandier (''J.&nbsp;rupestris'' Engelm.)
| Texas black walnut
|
*''J.&nbsp;microcarpa'' var. ''microcarpa''
*''J.&nbsp;microcarpa'' var. ''stewartii'' (Johnston) Manning
| United States
|-
|
|''[[Juglans mollis|J.&nbsp;mollis]]'' Engelm.
|Mexican walnut
|
| Mexico
|-
|[[File:Juglans neotrop3.jpg|120px]]
|''[[Juglans neotropica|J.&nbsp;neotropica]]'' Diels (''J.&nbsp;honorei'' Dode)  
|Andean walnut, ''cedro negro'', ''cedro nogal'', ''nogal'', ''nogal Bogotano''
|
| Colombia, Ecuador, and Peru
|-
|[[File:Black Walnut nut and leave detail.JPG|120px]]
|''[[Juglans nigra|J.&nbsp;nigra]]'' L. 
|Eastern black walnut
|
|Canada, United States
|-
|[[File:Juglans olanchana.jpg|120px]]
|''[[Juglans olanchana|J.&nbsp;olanchana]]'' Standl. & L.O.Williams 
|''cedro negro'', ''nogal'', walnut
|
*''J.&nbsp;olanchana'' var. ''olanchana''
*''J.&nbsp;olanchana'' var. ''standleyi''
|Central America, Mexico
|-
|
|''[[Juglans soratensis|J.&nbsp;soratensis]]'' Manning
|
|
|Bolivia
|-
|
|''[[Juglans steyermarkii|J.&nbsp;steyermarkii]]'' Manning 
|Guatemalan walnut
|
|Guatemala
|-
|
|''[[Juglans venezuelensis|J.&nbsp;venezuelensis]]'' Manning 
|Venezuelan walnut
|
| Venezuela
|-
! rowspan="1" style="text-align:center;"| Section ''Trachycaryon''
| rowspan="1"|  Leaves are very large (40–90&nbsp;cm), with 11–19 broad leaflets, softly downy, margins serrated. The wood is soft.   Fruits are borne in clusters of two to three.  The nuts have a thick, rough shell bearing distinct, sharp ridges. Native to eastern North America.
|[[File:Juglans cinerea 001.JPG|120px]]
|''[[Juglans cinerea|J.&nbsp;cinerea]]'' L.
|Butternut
|
| Canada, United States
|-
|}

The best-known member of the genus is the [[Juglans regia|Persian walnut]] (''J.&nbsp;regia'', literally "royal walnut"), native from the [[Balkans]] in southeast Europe, southwest and central Asia to the Himalaya and southwest China. Walnuts are a traditional feature of [[Iranian cuisine]]; the nation has extensive orchards which are an important feature of regional economies. In [[Kyrgyzstan]] alone, there are 230,700 ha of walnut-fruit forest, where ''J.&nbsp;regia'' is the dominant overstory tree (Hemery and Popov 1998).  In non-European English-speaking nations, the nut of the ''J.&nbsp;regia'' is often called the "English walnut";  in Great Britain, the "common walnut."

The [[Black Walnut|eastern black walnut]] (''J.&nbsp;nigra'') is a common species in its native eastern North America, and is also widely cultivated elsewhere. The nuts are edible, and though they are often used in expensive baked goods, the Persian walnut is preferred for everyday use because it is easier to extract the nutmeat. The wood is particularly valuable.

The [[Juglans hindsii|Hinds' black walnut]] (''J.&nbsp;hindsii'') is native to northern California, where it has been widely used commercially as a rootstock for ''J.&nbsp;regia'' trees.  Hinds' black walnut shells do not have the deep grooves characteristic of the eastern black walnut.

[[File:Juglans ailantifolia.jpg|thumb|Japanese walnut foliage and nuts]]
The [[Japanese walnut]] (''J.&nbsp;ailantifolia'') is similar to butternut, distinguished by the larger leaves up to 90&nbsp;cm long, and round (not oval) nuts. The variety ''cordiformis'', often called the '''heartnut''' has heart-shaped nuts; the common name of this variety is the source of the sectional name Cardiocaryon.

The [[Butternut (tree)|butternut]] (''J.&nbsp;cinerea'') is also native to eastern North America, where it is currently [[endangered species|endangered]] by an introduced disease, [[butternut canker]], caused by the [[fungus]] ''[[Sirococcus clavigignenti-juglandacearum]]''. Its leaves are 40–60&nbsp;cm long, the fruits are oval, the shell has very tall, very slender ridges, and the kernel is especially high in fat.

====Hybrids====
*''J.&nbsp;×&nbsp;bixbyi'' Rehd.—''J.&nbsp;ailantifolia'' x ''J.&nbsp;cinerea''
*''J.&nbsp;×&nbsp;intermedia'' Carr.—''J.&nbsp;nigra'' x ''J.&nbsp;regia''
*''J.&nbsp;×&nbsp;notha'' Rehd.—''J.&nbsp;ailantifolia'' x ''J.&nbsp;regia''
*''J.&nbsp;×&nbsp;quadrangulata'' (Carr.) Rehd.—''J.&nbsp;cinerea'' x ''J.&nbsp;regia''
*''J.&nbsp;×&nbsp;sinensis'' (D. C.) Rehd.—''J.&nbsp;mandschurica'' x ''J.&nbsp;regia''
*''J.&nbsp;×&nbsp;paradox'' Burbank—''J.&nbsp;hindsii'' x ''J.&nbsp;regia''
*''J.&nbsp;×&nbsp;royal'' Burbank—''J.&nbsp;hindsii'' x ''J.&nbsp;nigra''