Walnut

Article By:

MacDaniels, Laurence H. Horticultural Section, School of Integrative Plant Science, College of Agriculture and Life Sciences, Cornell University, Ithaca, New York.

Neely, Dan Illinois Natural History Survey, Urbana, Illinois.

Last reviewed:January 2020

DOI:https://doi.org/10.1036/1097-8542.737600

The common name applied to about a dozen species of large deciduous trees in the genus Juglans, and the edible nut of these trees. Walnut trees are widely distributed over temperate North America and South America, southeastern Europe, and central and eastern Asia. Trees belonging to the genus Juglans (order Fagales) are characterized by pinnately compound, aromatic leaves and chambered or laminate pith (the central zone of parenchymatous tissue that occurs in most vascular plants and is surrounded by vascular tissue) [Fig. 1]. The staminate (male) flowers are borne in unbranched catkins on the previous season's growth, and the pistillate (female) flowers are terminal on the current season's shoots. Pollination is accomplished by wind. The shells of the nuts of most species are deeply furrowed or sculptured. See also: Fagales; Horticultural crops; Nut crop culture; Pith; Tree

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