Walnut Classification and Species
Species and classification
Sect. Juglans. Leaves large (20-45 cm) with 5-9 broad leaflets,
hairless, margins entire. Wood hard. Southeast Europe to central Asia.
- Juglans regia L. (J. duclouxiana Dode, J. fallax Dode,
J. orientis Dode) - Persian Walnut, Carpathian, or Common Walnut
- Juglans sigillata Dode - Iron Walnut (doubtfully distinct from J.
Sect. Rhysocaryon. Leaves large (20-50 cm) with 11-23 slender
leaflets, finely pubescent, margins serrated. Wood hard. North America, South
- Juglans australis Griseb. (J. boliviana Dode) - Argentine
- Juglans brasiliensis Dode - Brazilian Walnut
- Juglans californica S.Wats. - California Walnut
- Juglans hindsii (Jepson) R.E.Smith - Hinds' Walnut
- Juglans hirsuta Manning - Nuevo Leon Walnut
- Juglans jamaicensis C.DC. (J. insularis Griseb.) - West
Juglans major (Torrey) Heller (J. arizonica Dode, J.
elaeopyron Dode, J. torreyi Dode) - Arizona Walnut
- Juglans major var. glabrata Manning
Juglans microcarpa Berlandier (J. rupestris Engelm.) - Texas
Walnut or Little Walnut
- Juglans microcarpa var. stewartii (Johnston) Manning
- Juglans mollis Engelm. - Mexican Walnut
- Juglans neotropica Diels (J. honorei Dode) - Andean
- Juglans nigra L. - Black Walnut
- Juglans olanchana Standl. & L.O.Williams -
- Juglans peruviana Dode - Peruvian Walnut
- Juglans soratensis Manning -
- Juglans steyermarkii Manning - Guatemalan Walnut
- Juglans venezuelensis Manning - Venezuela Walnut
Sect. Cardiocaryon. Leaves very large (40-90 cm) with 11-19 broad
leaflets, softly downy, margins serrated. Wood soft. Northeast Asia, eastern
- Juglans ailantifolia Carr. (J. cordiformis Maxim., J.
sieboldiana Maxim.) - Japanese Walnut
- Juglans cinerea L. - Butternut
- Juglans mandschurica Maxim. (J. cathayensis Dode, J.
formosana Hayata, J. hopeiensis Dode, J. stenocarpa Maxim.) -
Chinese Walnut or Manchurian Walnut
The best-known member of the genus is the Persian Walnut (Juglans regia),
native from the Balkans in southeast Europe, southwest & central Asia to the
Himalaya and southwest China.
The scientific name Juglans is from the Latin jovis glans, "Jupiter's nut",
and regia, "royal". Its common name, Persian walnut, indicates its origins in
Persia (Iran) in southwest Asia; 'walnut' derives from the Germanic wal- for
"foreign", recognising that it is not a nut native to northern Europe. In Kyrgyzstan
alone there are 230,700 ha of walnut-fruit forest, where J. regia is the
dominant overstorey (Hemery and Popov 1998). This is the species which is widely
cultivated for its delicious nuts. J. regia is also called English walnut
because English merchant marines once controlled its world commerce.
The Black Walnut (Juglans nigra) is a common species in its native eastern
North America, and is also widely cultivated elsewhere. The nuts are edible, but have
a smaller kernel and an extremely tough shell, and they are not widely grown for nut
The Butternut (Juglans cinerea) is also native to eastern North America,
where it is currently endangered by an introduced disease, butternut canker, caused
by the fungus Sirococcus clavigignenti. Its leaves are 40-60 cm long, and the
The Japanese Walnut (Juglans ailantifolia) is similar to Butternut,
distinguished by the larger leaves up to 90 cm long, and round (not oval) nuts.
- Juglans x bixbyi Rehd. - J. ailantifolia x J. cinerea
- Juglans x intermedia Carr. - J. nigra x J. regia
- Juglans x notha Rehd. - J. ailantifolia x J. regia
- Juglans x quadrangulata (Carr.) Rehd. - J. cinerea x J.
- Juglans x sinensis (D. C.) Rehd. - J. mandschurica x J.
- Juglans x paradox Burbank - J. hindsii x J. regia
- Juglans x royal Burbank - J. hindsii x J. nigra