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, 10–40 metres (33–131 ft) tall, with pinnate leaves 200–900 millimetres (7.9–35.4 in), with 5–25 leaflets; the shoots have chambered pith, a character shared with the wingnuts (Pterocarya), but not the hickories (Carya) in the same family.
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 Mexico, and two to four are native to Canada. A number of hickory species are used for their edible nuts, lumber or other wood and woodcraft products.
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 πτερον (pteron) "wing" + κάρυον (karyon) "nut".
Juglans nigra, the eastern American black walnut, is a species of deciduous tree in the walnut family, Juglandaceae, native to North America. It grows mostly in riparian zones, from southern Ontario, west to southeast South Dakota, south to Georgia, northern Florida and southwest to central Texas. Wild trees in the upper Ottawa Valley may be an isolated native population or may have derived from planted trees.
Juglans cinerea, commonly known as butternut or white walnut, is a species of walnut native to the eastern United States and southeast Canada.
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 Caucasus eastward to the Kashmir region. It is widely cultivated across Asia, Northern America and Europe.
Juglans ailantifolia, the Japanese walnut, is a species of walnut native to Japan and Sakhalin. It is a deciduous tree growing to 20 m (66 ft) tall, rarely 30 m (98 ft), and 40–80 cm (16–31 in) stem diameter, with light grey bark. The leaves are pinnate, 50–90 cm (20–35 in) long, with 11–17 leaflets, each leaflet 7–16 cm (2.8–6.3 in) long and 3–5 cm (1.2–2.0 in) broad. The whole leaf is downy-pubescent, and a somewhat brighter, yellower green than many other tree leaves. The male flowers are inconspicuous yellow-green catkins produced in spring at the same time as the new leaves appear. The female flowers have pink/red pistils. The fruit is a nut, produced in bunches of 4–10 together; the nut is spherical, 3–5 cm long and broad, surrounded by a green husk before maturity in mid autumn.
Juglone, also called 5-hydroxy-1,4-naphthalenedione (IUPAC) is a phenolic organic compound with the molecular formula C10H6O3. In the food industry, juglone is also known as C.I. Natural Brown 7 and C.I. 75500. It is insoluble in benzene but soluble in dioxane, from which it crystallizes as yellow needles. It is an isomer of lawsone, which is the active dye compound in the henna leaf.
Aesculus californica, commonly known as the California buckeye or California horse-chestnut, is a species of buckeye native to California and southwestern Oregon.
Pachira aquatica is a tropical wetland tree in the mallow family Malvaceae, native to Central and South America where it grows in swamps. It is known by its common names Malabar chestnut, French peanut, Guiana chestnut, Provision tree, Saba nut, Monguba (Brazil), Pumpo (Guatemala) and is commercially sold under the names Money tree and Money plant. This tree is sometimes sold with a braided trunk and is commonly grown as a houseplant, although more commonly what is sold as a "Pachira aquatica" houseplant is in fact a similar species, P. glabra.
Juglans californica, the California black walnut, also called the California walnut, or the Southern California black walnut, is a large shrub or small tree of the walnut family, Juglandaceae, endemic to the Central Valley and the Coast Range valleys from Northern to Southern California.
Fraxinus mandshurica, the Manchurian ash, is a species of Fraxinus native to northeastern Asia in northern China, Korea, Japan and southeastern Russia.
Juglans australis, the nogal criollo, is a species of plant in the Juglandaceae family. This large, fast-growing tree can grow to 20 m (66 ft) tall at elevations of 0.5—1.5 km in the Southern Andean Yungas, montane cloud forests on the eastern slopes of the Andes in Tucumán, Salta, and Jujuy provinces of Argentina and Tarija and Chuquisaca departments of Bolivia. It is threatened by habitat loss.
Juglans neotropica is a species of plant in the Juglandaceae family. It is found in Colombia, Ecuador, and Peru. It is threatened by habitat loss. Common names include Colombian walnut, Ecuadorian walnut, Andean walnut, nogal, cedro negro, cedro nogal, and nogal Bogotano.
Oreomunnea mexicana is a species of plant in the family Juglandaceae, which grows in the tropical rain forests of Mexico, Guatemala, Nicaragua, Costa Rica, and Panama at altitudes from 1–1.7 km. Common names include guayabo amarillo and remiendo. The chromosome number is 2n = 32.
Juglans microcarpa, known also as the little walnut, Texas walnut, Texas black walnut or little black walnut, is a large shrub or small tree which grows wild along streams and ravines in Texas, New Mexico, Oklahoma, and Kansas, and the northernmost states of Mexico. It produces nuts with a width of 1/2—3/4 in. The pinnately compound leaves bear 7—25 untoothed to finely-toothed leaflets, each 1/4—1/2 in wide. It is found at elevations ranging from 700 ft to 6700 ft.
Iris mandshurica is a species in the genus Iris; it is also in the subgenus of Iris and in the Psammiris section. It is a rhizomatous perennial, it is found in Russia, China, and Korea. It has green sword-like leaves, smooth green stem and yellow flowers, with yellow-purple veining and a yellow beard. It is cultivated as an ornamental plant in temperate regions.
Acer barbinerve, commonly known as bearded maple, is an Asian species of maple found in Korea, eastern Russia, and northeastern China.
Meliosma oldhamii is a species of deciduous tree in the family Sabiaceae, which grows up to 20 meters in height. It has a narrow crown when young, and it becomes more wide-spreading with age. It is endemic to China, Japan, and Korea.
Juglans hopeiensis, also known as Ma walnut, is a species of walnut native to northern Hebei Province. Some scholars believe that the species is a hybrid of Juglans regia and Juglans mandshurica. Currently, it is a threatened tree species.
