The Juglandaceae are a plant family known as the walnut family. They are

tree In botany, a tree is a perennial plant with an elongated stem, or trunk, usually supporting branches and leaves. In some usages, the definition of a tree may be narrower, including only woody plants with secondary growth, plants that are ...

s, or sometimes shrubs, in the order

Fagales The Fagales are an order of flowering plants, including some of the best-known trees. The order name is derived from genus ''Fagus'', beeches. They belong among the rosid group of dicotyledons. The families and genera currently included are a ...

. Members of this family are native to the

Americas The Americas, which are sometimes collectively called America, are a landmass comprising the totality of North and South America. The Americas make up most of the land in Earth's Western Hemisphere and comprise the New World. Along with th ...

Eurasia Eurasia (, ) is the largest continental area on Earth, comprising all of Europe and Asia. Primarily in the Northern and Eastern Hemispheres, it spans from the British Isles and the Iberian Peninsula in the west to the Japanese archipelago a ...

, and

Southeast Asia Southeast Asia, also spelled South East Asia and South-East Asia, and also known as Southeastern Asia, South-eastern Asia or SEA, is the geographical United Nations geoscheme for Asia#South-eastern Asia, south-eastern region of Asia, consistin ...

. The nine or ten genera in the family have a total of around 50 species, and include the commercially important

nut Nut often refers to: * Nut (fruit), fruit composed of a hard shell and a seed, or a collective noun for dry and edible fruits or seeds * Nut (hardware), fastener used with a bolt Nut or Nuts may also refer to: Arts, entertainment, and media Co ...

-producing trees

walnut A walnut is the edible seed of a drupe of any tree of the genus ''Juglans'' (family Juglandaceae), particularly the Persian or English walnut, '' Juglans regia''. Although culinarily considered a "nut" and used as such, it is not a true ...

(''Juglans''),

pecan The pecan (''Carya illinoinensis'') is a species of hickory native to the southern United States and northern Mexico in the region of the Mississippi River. The tree is cultivated for its seed in the southern United States, primarily in Georgia, ...

(''Carya illinoinensis''), and

hickory Hickory is a common name for trees composing the genus ''Carya'', which includes around 18 species. Five or six species are native to China, Indochina, and India (Assam), as many as twelve are native to the United States, four are found in Mexi ...

(''Carya''). The Persian walnut, ''

Juglans regia ''Juglans regia'', the Persian walnut, English walnut, Carpathian walnut, Madeira walnut, or especially in Great Britain, common walnut, is an Old World walnut tree species native to the region stretching from the Balkans eastward to the Himala ...

'', is one of the major nut crops of the world. Walnut, hickory, and gaulin are also valuable timber trees while pecan wood is also valued as cooking fuel.

Description

Members of the walnut family have large, aromatic leaves that are usually alternate, but opposite in ''

Alfaroa ''Alfaroa'' is a genus of evergreen trees in the Juglandaceae family of the Fagales, growing in montane and submontane tropical rain forests in Central America. The wood is characterized by solid pith, pink heartwood, and vessels with scalarifor ...

'' and ''

Oreomunnea ''Oreomunnea'' is a genus of two species of flowering plants in the family Juglandaceae, native to southern Mexico and Central America, where they occur in montane rainforest.Manning, W. E. (1979). The Classification within the Juglandaceae. ''An ...

''. The

leaves A leaf (plural, : leaves) is any of the principal appendages of a vascular plant plant stem, stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", wh ...

are pinnately compound or ternate, and usually 20–100 cm long. The trees are

wind-pollinated Anemophily or wind pollination is a form of pollination whereby pollen is distributed by wind. Almost all gymnosperms are anemophilous, as are many plants in the order Poales, including grasses, sedges, and rushes. Other common anemophilous pla ...

, and the flowers are usually arranged in

catkin A catkin or ament is a slim, cylindrical flower cluster (a spike), with inconspicuous or no petals, usually wind-pollinated (anemophilous) but sometimes insect-pollinated (as in ''Salix''). They contain many, usually unisexual flowers, arranged cl ...

s. The fruits of the Juglandaceae are often confused with

drupes In botany, a drupe (or stone fruit) is an indehiscent fruit in which an outer fleshy part (exocarp, or skin, and mesocarp, or flesh) surrounds a single shell (the ''pit'', ''stone'', or '' pyrena'') of hardened endocarp with a seed (''kernel'') ...

but are

accessory fruit An accessory fruit is a fruit in which some of the flesh is derived not from the floral ovary but from some adjacent tissue exterior to the carpel.Esau, K. 1977. ''Anatomy of seed plants''. John Wiley and Sons, New York. Accessory fruits are u ...

because the outer covering of the fruit is technically an

involucre In botany, a bract is a modified or specialized leaf, especially one associated with a reproductive structure such as a flower, inflorescence axis or cone scale. Bracts are usually different from foliage leaves. They may be smaller, larger, or o ...

and thus not morphologically part of the carpel; this means it cannot be a drupe but is instead a drupe-like nut.

Taxonomy

The known living genera are grouped into subfamilies, tribes, and subtribes as follows: * Subfamily

Rhoipteleoideae ''Rhoiptelea'' is a monotypic genus of flowering plants in the family Juglandaceae. It contains a single species, ''Rhoiptelea chiliantha'', commonly known as the horsetail tree. This genus was previously recognized in its own family, Rhoipteleac ...

Reveal ** ''

Rhoiptelea ''Rhoiptelea'' is a monotypic genus of flowering plants in the family Juglandaceae. It contains a single species, ''Rhoiptelea chiliantha'', commonly known as the horsetail tree. This genus was previously recognized in its own family, Rhoipteleac ...

'' Diels & Hand.-Mazz. 1932 * Subfamily Engelhardioideae Iljinskaya 1990 ** ''

'' Standl. 1927—gaulin ** ''

Engelhardia ''Engelhardia'' is a genus of seven species of trees in the family Juglandaceae, native to southeast Asia from northern India east to Taiwan, Indonesia and the Philippines. The genus name is commonly misspelled "''Engelhardtia''", a "correctio ...

'' Lesch. ex Blume 1825–1826—cheo ** ''

'' Oerst. 1856 * Subfamily

Juglandoideae Juglandoideae is a subfamily of the walnut family Juglandaceae. This clade was first described by Koidzumi in 1937 by the name "Drupoideae," based on the drupe-like fruits of ''Juglans'' and ''Carya''. This name was rejected because it was not ...

Eaton 1836 ** Tribe

Platycaryeae Platycaryeae is a tribe of flowering plants in the family Juglandaceae, and comprising a single living genus ''Platycarya''. The tribe is now native to eastern Asia in China, Korea, and Japan.Flora of China''Platycarya''/ref>Flora of China''Pla ...

Nakai 1933 *** ''

Platycarya ''Platycarya'' is a genus of flowering plants in the family Juglandaceae native to eastern Asia in China, Korea, and Japan.Flora of China''Platycarya''/ref>Flora of China''Platycarya strobilacea''/ref> It is a deciduous tree growing to 15 m ta ...

'' Siebold & Zucc. 1843 ** Tribe Juglandeae Rchb. 1832 *** Subtribe

Caryinae Caryinae is a subtribe of the tribe Juglandeae subfamily in the Juglandaceae. The Latin description of this subtribe is as follows: Medulla solida; pollenis grana 3-pora; bracteolae pis- tillatae 2 (ve1 3–5), ad apicem ovarii connatae; positi ...

D.E. Stone & P. S. Manos 2001 **** ''

Carya Hickory is a common name for trees composing the genus ''Carya'', which includes around 18 species. Five or six species are native to China, Indochina, and India (Assam), as many as twelve are native to the United States, four are found in Mexi ...

'' Nutt. 1818—hickory and pecan **** '' Annamocarya'' A.Chev. 1941 (sometimes included in ''Carya'') *** Subtribe

Juglandinae Juglandinae is a subtribe of the Juglandeae tribe, of the Juglandoideae subfamily, in the Juglandaceae family. Walnut tree species make up the genus ''Juglans Walnut trees are any species of tree in the plant genus ''Juglans'', the type ge ...

D.E. Stone & P. S. Manos 2001 **** ''

Cyclocarya ''Cyclocarya'' is a genus of flowering plants in the family Juglandaceae, comprising a single species ''Cyclocarya paliurus'' (qing qian liu or wheel wingnut), formerly treated in the genus ''Pterocarya'' as ''Pterocarya paliurus''. It is native ...

'' Iljinsk 1953—wheel wingnut **** ''

Juglans Walnut trees are any species of tree in the plant genus ''Juglans'', the type genus of the family Juglandaceae, the seeds of which are referred to as walnuts. All species are deciduous trees, tall, with pinnate leaves , with 5–25 leaflets ...

'' L. 1753—walnut **** ''

Pterocarya ''Pterocarya'', often called wingnuts in English, are trees in the walnut family Juglandaceae. They are native to Asia. The botanic name is from Ancient Greek (''pteron'') "wing" + (''karyon'') " nut". Description ''Pterocarya'' are deciduous ...

'' Kunth 1824—wingnut

Systematics

Modern

molecular phylogenetics Molecular phylogenetics () is the branch of phylogeny that analyzes genetic, hereditary molecular differences, predominantly in DNA sequences, to gain information on an organism's evolutionary relationships. From these analyses, it is possible to ...

suggest the following relationships:

References

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