Juglans major

Common names:Arizona Black Walnut, Nogal.

Family:Juglandaceae

Synonymy:Juglans rupestris Engelm. var. major. Torr.
Etymology: Juglans is “walnut” in latin. Major implies large, tall, extensive, or spacious.

Identification

Growth form:Arizona Walnut is a tree, grows to about 40’.
Bark:Thick and deeply furrowed. Greyish color to brown.
Leaves: Leaves are pineately compound and alternate. Leaves usually less than 3’, with 9-13 leaflets. Leaflets are ovate, yellow-green in color, and have distinctive walnut aroma. The two leaflets closest to the trunk point back toward the trunk.
Inflorescence/flowers:Green, catkins on male. Females smaller, becoming nuts on inside.

Fruit:Smooth, globe shaped nut with thick shell, brown in color. Small kernel in center. Nut is foodstuff for some animals, and is quite tasty if it can be accessed. .

Similar species:Western soapberry and Ailanthus. Juglans major can be easily determined from these by the proximal leaves pointing toward the trunk.

Ecology

Life history:Arizona walnut is a long-lived tree, to 400 years. Growth rate is slow, only 1.5’ per year until maturity. It is a facultative riparian species, and is the only walnut to occur in the desert.
Native/introduced: Native.
Phenology:Catkins produced in the spring. Fruits mature in about 3 months and are ripe usually between July and September. Trees produce many fruits every 2-3 years, seemingly dependant on spring precipitation.

Distribution:Occurs in many habitats, from desert to mountain. Does best in riparian areas. Elevationally occurs from 2500’-6500’, with minor range extensions to 8500’.

Uses

Wildlife:Food for squirrels and others. Nesting habitat for birds.

Economic: Dark chocolate colored wood with excellent grain patterns prized for gun stocks, cabinetry, picture frames, etc. Not overly useful for lumber.

References

  1. Rehder, Alfred. 1940. Manual of cultivated trees and shrubs. New York: MacMillan Co.. 996 p.
  2. Minckley, W. L.; Brown, David E. 1982. Wetlands. In: Brown, David E., ed. Biotic communities of the American Southwest--United States and Mexico. Desert Plants. 4(1-4): 223-287.
  3. Layser, Earle F.; Schubert, Gilbert H. 1979. Preliminary classification for the coniferous forest and woodland series of Arizona and New Mexico. Res. Pap. RM-208. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky MountainForest and Range Experiment Station. 27
  4. Brinkman, Kenneth A. 1974. Juglans L. walnut. In: Schopmeyer, C. S.,ed. Seeds of woody plants in the United States. Agric. Handb. 450. Washington, DC: U.S. Department of Agriculture, Forest Service: 454-459.
  5. Benson, Lyman; Darrow, Robert A. 1981. The trees and shrubs of the Southwestern deserts. Tucson, AZ: The University of Arizona Press.
  6. Campbell, C. J. 1973. Pressure bomb measurements indicate water availability in a southwestern riparian community. Res. Note RM-246. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky MountainForest and Range Experiment Station. 4 p.
  7. Stromberg, Juliet C.; Patten, Duncan T. 1990. Variation in seed size of a southwestern riparian tree, Arizona walnut (Juglans major). American Midland Naturalist. 124(2): 269-277.
  8. Stromberg, Juliet C.; Patten, Duncan T. 1990. Flower production and floral ratios of a southwestern riparian tree, Arizona walnut (Juglans major). American Midland Naturalist. 124(2): 278-288.
  9. Szaro, Robert C. 1990. Southwestern riparian plant communities: site characteristics, tree species distributions, and size-class structures. Forest Ecology and Management. 33/34: 315-334.