The Juglandaceae or Walnut Family is a relatively small family of most trees found in North, Central and South America and in Asia. The family consists of mostly deciduous trees with pinnately compound leaves including the Walnuts, Hickory and Pecans.
World-wide, the largest genera in the Walnut family include; Carya (27 species); Juglands (21 species), Engelhardtia (12 species) and Alfaroa ( 8 species). Not all sources agree on the exact number of species for each genus.
Carya is the genus for Hickory and Pecan trees which are deciduous trees with pinnately compound leaves primarily in North American and mostly in the United States but also found in Mexico and Canada. Hickory trees are also Native to China Indochina and India.
Juglands is the genus for Walnut trees which are also deciduous species with pinnate leaves that are mostly large trees and some may grow to 130 feet tall. The largest number of Walnut trees are found in North and South America. In North America they are found in southeast Canada west to California and south to Argentina in South America.
Engelhardia are deciduous trees native to southeast Asia, northern India and a few species in China. Most of the species are found in southeast Asia. According to the Flora of China, the genus Engelhardia appears to lack sufficient data as the taxonomy suffers from a lack of specimens.
The genus Alfaroa are non-deciduous trees that grow in montaine and sub-montaine tropical rain forests in Central America. The evergreen leaves are mostly alternate.
In Juglandaceae Walnut, Pecan and Hickory trees are the most economically important species. They are all commercially grown for timber, landscape and nuts which are used in a host of recipes including Baklava and Turkish cuisine. The two most commercially important species are Junglands regia for timber and nuts, and Juglands nigra for timber. Several cultivars are grown for landscape purposes. Pecans produced by species of Carya are also important commercially.
In North America, according to the USDA Plants Database, there are 4 genera with 46 accepted taxa overall in the Juglandaceae family. World-wide, The Plant List identifies 12 plant genera with 89 accepted species names and a further 142 scientific plant names of infraspecific rank for the family Juglandaceae.
Juglans major, Arizona Walnut