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Scientific Name: Juglands nigra

Author: Kwon, Sam Soonchae

Common Names: "black walnut"

Higher taxa: *According to the Cronquist System of Classification (Jones, 1986)
Division MAGNOLIOPHYTA
Class MAGNOLIOPSIDA (dicots)
Subclass Hamamelidae
      Order Juglandales
        Family Juglandaceae
              Genus Juglands
                    Species nigra
Identification:

1. J. nigra L., Black Walnut. Pith light brown. Leaflets 9-19, lanceolate or ovate, 3-15 cm long, 1.5 - 5.5 cm wide, pubescent beneath, acuminate, serrate, base rounded, oblique, or cordate, sessile or subsessile; petioles 6.5-14 cm long; rachis and petiole glandular pubescent. Fruit globose, glabrous, usually 4-5 cm in diameter. (Radford,363)


Dendrology: Leaves: alternate, pinnately compound, upto 19 leaflets. Buds: gray, pubescent, essentially naked. Twigs: pith chambered, leaf scar lacking hairy fringe. Bark: dark brown with deep narrow furrows and thin interlacing ridges, chocolate brown color when scraped. Fruit: globose nut, husk smooth, shell corrugations rounded. Most valuable timeber species in the U.S. Odor of nut, bark and branches strong. (Heywood, 569)

Authority and Reference: Carl Linnaeus , Species Plantarium (Hooker,)

Location described: London: Herbarium, The Linnean Society of London, Burlinton House, Piccadilly, London, WIV OLQ, England, Great Britain (Type: not known)(Hooker,)

GENERAL DISTRIBUTION :
Black walnut is found throughout the eastern United States. It grows as far north as southern Minnesota, southern Wisconsin, southern Michigan, and southern Ontario. Isolated populations occur in the southern half of New York, Vermont, western Massachusetts, and northwestern Connecticut. Its range extends south to northwestern Florida, and to Mississippi, Arkansas, and Louisiana except for the Mississippi Valley and Delta regions. In the Midwest, isolated populations occur in eastern Texas, western Oklahoma, central Kansas, and southeastern South Dakota" (www. dept of agriculture).

REGENERATION PROCESSES :
Seed production: Black walnut produces abundant seed crops irregularly, perhaps twice in 5 years. Although open-grown trees produce seed as early as 8 years after planting, the minimum seed-bearing age for commercial quantities of seed is about 12 years. Best seed production begins when the tree is about 30 years old and continues for another 100 years .

Dispersal: Black walnut seed is heavy. The seeds are dispersed by squirrels carrying seed from beneath the tree and burying them at a distance .

Seedling development: Many black walnut seedlings germinate from the nuts cached by squirrels in the fall. Normal freezing and thawing usually causes the seeds to break dormancy the following spring, but germination is often delayed, sometimes until the second year .

Vegetative reproduction: Small black walnut trees usually sprout from the stump when they are cut or killed back by fire. Shoots originating high on the older stumps often decay, but shoots from the root crown generally are free from defect" (www. dept of agriculture)

SITE CHARACTERISTICS :
Black walnut is found on a variety of sites but grows best on deep, well-drained neutral soils that are moist and fertile . It grows slowly on wet bottomlands, dry ridges, and slopes. Black walnut is common on limestone soils and grows extremely well on deep loams and fertile alluvial deposits. Good agricultural soils are generally favorable sites for black walnut. In the Appalachians, the best wlanut trees are found on bottomlands and coves below 4,000 feet (1,200 m) .

Principal associates are identified in the Distribution and Occurrence frame. Other common tree associates include American elm (Ulmus americana), hackberry (Celtis laevigata), green ash (Fraxinus pennsylvanica), box elder (Acer negundo), and butternut (Juglans cinerea)" (www. dept of agriculture)

SUCCESSIONAL STATUS :
Black walnut is classified as shade intolerant. In mixed forest stands, it must be dominant to survive, although it can survive in the relatively light shade of black locust . Black walnut is found in many of the climax associations but because of its intolerance is not classified as a climax tree in the strict sense. In general, black walnut maintains itself in most stands as scattered single trees occupying openings in the canopy(www. dept of agriculture) .