Practical
Plants

Juglans major

Arizona Walnut

a perennial woody deciduous member of the Juglans genus in the family Juglandaceae.

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Taxonomy and growth

Genus
Juglans
Life cycle
perennial
Foliage
deciduous
Woodiness
woody
Growth rate
vigorous
Height
15 m
Fertility
Self fertile, Wind
Flower type
monoecious
Pollinators
Wind

Uses

Edible uses

This section contains historical Plants For A Future notes marked noncommercial.

Seed - raw or cooked[13]. The seed is rather small, but it is sometimes eaten[16][5][8]. Of little value[6]. The seed is large and sweet[11] with a thick shell[10][11]. There are about 45 seeds to the pound[11]. The seeds are 25 - 40mm in diameter[12]. An edible oil is obtained from the seed, it tends to go rancid quickly.

Product or use
Oil
Plant part
Seed

Material uses

This section contains historical Plants For A Future notes marked noncommercial.

This species is sometimes used as a rootstock[8]. A golden brown dye can be obtained from the seed husks[13]. A light brown dye is obtained from the young twigs[13]. Plants produce chemicals which can inhibit the growth of other plants. These chemicals are dissolved out of the leaves when it rains and are washed down to the ground below, reducing the growth of plants under the tree[7][9][4]. The roots of many members of this genus produce substances that are toxic to many plant species, especially apples (Malus species), members of the Ericaceae, Potentilla spp and the white pines (certain Pinus spp.)[10]. Wood - this very attractive wood rivals that of J. nigra, the black walnut, in quality[12]. However, the limited range and smaller size of the tree have restricted its use[12].

Product or use
Dye
Product or use
Herbicide

Ecology and functions

Ecosystem niche
Canopy

Rootstock

Environment

Range
Southern N. America - New Mexico to Arizona.
Habitat
Dry rocky ravines and stream beds, 700 - 2300 metres[12].
Light
full sun
Shade tolerance
no shade
Water
moderate
Hardiness
Zone 9+
Soil textures
sandy, loamy, clay
Soil pH
acid, neutral, alkaline
Drainage
well drained
Tolerates Nutritionally Poor Soil
No
Drought
intolerant

Propagation

This section contains historical Plants For A Future notes marked noncommercial.

The seed is best sown as soon as it is ripe in individual deep pots in a cold frame[15]. You need to protect it from mice, birds, squirrels etc. The seed usually germinates in late winter or the spring. Plant out the seedlings into their permanent positions in early summer and give some protection from the cold for their first winter or two. The seed can also be stored in cool moist conditions (such s the salad compartment of a fridge) over the winter and sown in early spring but it may then require a period of cold stratification before it will germinate[14][15][3]. Germination rates are usually less than 50%[11].

Cultivation

This section contains historical Plants For A Future notes marked noncommercial.

Requires a deep well-drained loam and a sunny position sheltered from strong winds[1][2]. Prefers a slightly alkaline soil[10]. Plants are fast-growing when young[11]. This species is closely related to and sometimes considered to be no more than a sub-species of J. microcarpa[2][12]. It hybridizes with that species where their ranges overlap[12]. If it is a distinct species then perhaps its correct name should be J. torreyi[2]. Trees produce good crops of seeds every 2 - 3 years in the wild[11]. Natural regeneration is very low because most seeds are consumed by wildlife[12]. Plants are fairly long-lived (to about 400 years) and produce a deep taproot, they are intolerant of root disturbance[1][2][12]. Seedlings should be planted out into their permanent positions as soon as possible and given some protection for their first winter or two since they are somewhat tender when young[1][2]. Flower initiation depends upon suitable conditions in the previous summer[10]. The flowers and young growths can be destroyed by even short periods down to -2°c, but fortunately plants are usually late coming into leaf[10]. Any pruning should only be carried out in late summer to early autumn or when the plant is fully dormant otherwise wounds will bleed profusely and this will severely weaken the tree[10]. Trees have a dense canopy which tends to reduce plant growth below them. We have no specific information for this species, but the roots of several members of this genus produce substances that are toxic to many plant species, especially apples (Malus species), members of the Ericaceae, Potentilla spp and the white pines (certain Pinus spp.)[10]. The leaves of many species also secrete substances that have an inhibitory affect on plants growing underneath them. All in all this is not a very good companion plant[K].

References

  1. F. Chittendon. RHS Dictionary of Plants plus Supplement. 1956 Oxford University Press 1951-00-00

    ↩1↩2↩3

  2. Bean. W. Trees and Shrubs Hardy in Great Britain. Vol 1 - 4 and Supplement. Murray 1981-00-00

    ↩1↩2↩3↩4↩5

  3. Dirr. M. A. and Heuser. M. W. The Reference Manual of Woody Plant Propagation. Athens Ga. Varsity Press 1987-00-00 ISBN 0942375009

    ↩

  4. McPherson. A. and S. Wild Food Plants of Indiana. Indiana University Press 1977-00-00 ISBN 0-253-28925-4

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  5. Yanovsky. E. Food Plants of the N. American Indians. Publication no. 237. U.S. Depf of Agriculture.

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  6. Kunkel. G. Plants for Human Consumption. Koeltz Scientific Books 1984-00-00 ISBN 3874292169

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  7. Philbrick H. and Gregg R. B. Companion Plants. Watkins 1979-00-00

    ↩

  8. Facciola. S. Cornucopia - A Source Book of Edible Plants. Kampong Publications 1990-00-00 ISBN 0-9628087-0-9

    ↩1↩2

  9. Riotte. L. Companion Planting for Successful Gardening. Garden Way, Vermont, USA. 1978-00-00 ISBN 0-88266-064-0

    ↩

  10. Huxley. A. The New RHS Dictionary of Gardening. 1992. MacMillan Press 1992-00-00 ISBN 0-333-47494-5

    ↩1↩2↩3↩4↩5↩6↩7

  11. Vines. R.A. Trees of North Texas University of Texas Press. 1982-00-00 ISBN 0292780206

    ↩1↩2↩3↩4↩5↩6

  12. Elias. T. The Complete Trees of N. America. Field Guide and Natural History. Van Nostrand Reinhold Co. 1980-00-00 ISBN 0442238622

    ↩1↩2↩3↩4↩5↩6↩7↩8

  13. Moerman. D. Native American Ethnobotany Timber Press. Oregon. 1998-00-00 ISBN 0-88192-453-9

    ↩1↩2↩3

  14. Sheat. W. G. Propagation of Trees, Shrubs and Conifers. MacMillan and Co 1948-00-00

    ↩

  15. McMillan-Browse. P. Hardy Woody Plants from Seed. Grower Books 1985-00-00 ISBN 0-901361-21-6

    ↩1↩2

  16. Sargent. C. S. Manual of the Trees of N. America. Dover Publications Inc. New York. 1965-00-00 ISBN 0-486-20278-X

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