Juglans major

Juglans major (Torr.) Heller

by Allen Zufelt, Native Plants Class 2002
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’. [5]
Roots:
Stem: Thick and deeply furrowed. Grayish color to brown.[4]
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. [4]
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. [7]
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. [6, 8, 9]
Native/introduced: Native.
Photosynthetic pathway:
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’ [1, 3, 2], with minor range extensions to 8500’.[9]

Uses
Wildlife: Food for squirrels and others. Nesting habitat for birds.[2]
Economic: Dark chocolate colored wood with excellent grain patterns prized for gun stocks, cabinetry, picture frames, etc. Not overly useful for lumber. [3]

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 Mountain Forest 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 Mountain Forest 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.

Juglans major (Torr.) Heller by Allen Zufelt, Native Plants Class 2002 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’. [5] Roots: Stem: Thick and deeply furrowed. Grayish color to brown.[4] 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. [4] 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. [7] 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. [6, 8, 9] Native/introduced: Native. Photosynthetic pathway: 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’ [1, 3, 2], with minor range extensions to 8500’.[9] Uses Wildlife: Food for squirrels and others. Nesting habitat for birds.[2] Economic: Dark chocolate colored wood with excellent grain patterns prized for gun stocks, cabinetry, picture frames, etc. Not overly useful for lumber. [3] 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 Mountain Forest 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 Mountain Forest 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.