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Useful Temperate Plants

Juglans californica

S.Watson

Juglandaceae

+ Synonyms

Common Name: California Walnut

No Image.

General Information

Juglans californica is a deciduous shrub or a small tree that usually grows around 6 - 9 metres tall, occasionally reaching 18 metres[
1735
Title
Notes on the Temperate Species of Juglans
Publication
Int. Dendrol. Soc. Year Book 107-130 2003
Author
Grimshaw J.M.
Publisher
 
Year
2003
ISBN
 
Description
 
].
The plant is harvested from the wild for local use as a food, medicine and source of materials. The tree is grown as an ornamental and sometimes used to restore native woodlands in California[
338
Title
IUCN Red List of Threatened Species
Publication
 
Author
 
Website
http://www.iucnredlist.org/
Publisher
 
Year
0
ISBN
 
Description
A list of plants under threat and facing possible extinction, usually with brief details of the threats and information on habitat.
]
Juglans californica is restricted to the southwest of Calicornia. The population size is unknown and the species can be dominant in woodland. Despite this there is continuing decline in population size due to threats from habitat loss and conversion, grazing of the habitat and increased occurrence of fire. There are also concerns for the future regeneration of the species and potential habitat availability due to a local growing human population which could put pressure on the species and its habitat. The plant is classified as 'Near Threatened' in the IUCN Red List of Threatened Species(2018)[
338
Title
IUCN Red List of Threatened Species
Publication
 
Author
 
Website
http://www.iucnredlist.org/
Publisher
 
Year
0
ISBN
 
Description
A list of plants under threat and facing possible extinction, usually with brief details of the threats and information on habitat.
].

Known Hazards

None known

Botanical References

11
Title
Trees and Shrubs Hardy in Great Britain. Vol 1 - 4 and Supplement.
Publication
 
Author
Bean. W.
Publisher
Murray
Year
1981
ISBN
-
Description
A classic with a wealth of information on the plants, but poor on pictures.
,
200
Title
The New RHS Dictionary of Gardening. 1992.
Publication
 
Author
Huxley. A.
Publisher
MacMillan Press
Year
1992
ISBN
0-333-47494-5
Description
Excellent and very comprehensive, though it contains a number of silly mistakes. Readable yet also very detailed.
,
270
Title
Flora of N. America
Publication
 
Author
 
Website
http://flora.huh.harvard.edu/fna/
Publisher
 
Year
0
ISBN
 
Description
An on-line version of the flora with an excellent description of the plant including a brief mention of plant uses.

Range

South-western N. America - southwestern California.

Habitat

Hillsides and canyons, growing in moist or dry gravelly soils along river courses and bottomlands[
229
Title
The Complete Trees of N. America. Field Guide and Natural History.
Publication
 
Author
Elias. T.
Publisher
Van Nostrand Reinhold Co.
Year
1980
ISBN
0442238622
Description
A very good concise guide. Gives habitats, good descriptions, maps showing distribution and a few of the uses. It also includes the many shrubs that occasionally reach tree proportions.
,
270
Title
Flora of N. America
Publication
 
Author
 
Website
http://flora.huh.harvard.edu/fna/
Publisher
 
Year
0
ISBN
 
Description
An on-line version of the flora with an excellent description of the plant including a brief mention of plant uses.
]. Locally common in oak woods below 750 metres[
71
Title
A California Flora.
Publication
 
Author
Munz P.A. & Keck D.D.
Publisher
University of California Press; Los Angeles
Year
1959
ISBN
-
Description
An excellent flora but no pictures. Not for the casual reader.
].

Properties

Conservation StatusNear Threatened
Edibility Rating *  *
Medicinal Rating *
HabitDeciduous Tree
Height6.00 m
Growth RateMedium
PollinatorsWind
Self-fertileYes
Cultivation StatusOrnamental, Wild

Cultivation Details

Juglans californica is native to the more or less Mediterranean climate of southern California, with its hot, dry summers and cooler, moist winters. It is not very hardy in most of the temperate zone, being able to tolerate short periods with temperatures down to between -5 and -10°c when dormant so long as the summer has been hot enough to fully ripen the wood. The young growth in spring is very susceptible to frost damage[
200
Title
The New RHS Dictionary of Gardening. 1992.
Publication
 
Author
Huxley. A.
Publisher
MacMillan Press
Year
1992
ISBN
0-333-47494-5
Description
Excellent and very comprehensive, though it contains a number of silly mistakes. Readable yet also very detailed.
].
Requires a deep well-drained loam and a sunny position sheltered from strong winds[
1
Title
RHS Dictionary of Plants plus Supplement. 1956
Publication
 
Author
F. Chittendon.
Publisher
Oxford University Press
Year
1951
ISBN
-
Description
Comprehensive listing of species and how to grow them. Somewhat outdated, it has been replaced in 1992 by a new dictionary (see [200]).
,
11
Title
Trees and Shrubs Hardy in Great Britain. Vol 1 - 4 and Supplement.
Publication
 
Author
Bean. W.
Publisher
Murray
Year
1981
ISBN
-
Description
A classic with a wealth of information on the plants, but poor on pictures.
]. Prefers a slightly alkaline soil[
200
Title
The New RHS Dictionary of Gardening. 1992.
Publication
 
Author
Huxley. A.
Publisher
MacMillan Press
Year
1992
ISBN
0-333-47494-5
Description
Excellent and very comprehensive, though it contains a number of silly mistakes. Readable yet also very detailed.
].
A fairly fast-growing tree in its native habitat, but quite short-lived, dying after about 125 - 150 years[
229
Title
The Complete Trees of N. America. Field Guide and Natural History.
Publication
 
Author
Elias. T.
Publisher
Van Nostrand Reinhold Co.
Year
1980
ISBN
0442238622
Description
A very good concise guide. Gives habitats, good descriptions, maps showing distribution and a few of the uses. It also includes the many shrubs that occasionally reach tree proportions.
].
Plants produce a deep taproot and they are intolerant of root disturbance[
1
Title
RHS Dictionary of Plants plus Supplement. 1956
Publication
 
Author
F. Chittendon.
Publisher
Oxford University Press
Year
1951
ISBN
-
Description
Comprehensive listing of species and how to grow them. Somewhat outdated, it has been replaced in 1992 by a new dictionary (see [200]).
,
11
Title
Trees and Shrubs Hardy in Great Britain. Vol 1 - 4 and Supplement.
Publication
 
Author
Bean. W.
Publisher
Murray
Year
1981
ISBN
-
Description
A classic with a wealth of information on the plants, but poor on pictures.
]. Seedlings should be planted out into their permanent positions as soon as possible and given some protection since they are somewhat tender when young[
1
Title
RHS Dictionary of Plants plus Supplement. 1956
Publication
 
Author
F. Chittendon.
Publisher
Oxford University Press
Year
1951
ISBN
-
Description
Comprehensive listing of species and how to grow them. Somewhat outdated, it has been replaced in 1992 by a new dictionary (see [200]).
,
11
Title
Trees and Shrubs Hardy in Great Britain. Vol 1 - 4 and Supplement.
Publication
 
Author
Bean. W.
Publisher
Murray
Year
1981
ISBN
-
Description
A classic with a wealth of information on the plants, but poor on pictures.
].
Flower initiation depends upon suitable conditions in the previous summer[
200
Title
The New RHS Dictionary of Gardening. 1992.
Publication
 
Author
Huxley. A.
Publisher
MacMillan Press
Year
1992
ISBN
0-333-47494-5
Description
Excellent and very comprehensive, though it contains a number of silly mistakes. Readable yet also very detailed.
]. 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[
200
Title
The New RHS Dictionary of Gardening. 1992.
Publication
 
Author
Huxley. A.
Publisher
MacMillan Press
Year
1992
ISBN
0-333-47494-5
Description
Excellent and very comprehensive, though it contains a number of silly mistakes. Readable yet also very detailed.
].
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[
200
Title
The New RHS Dictionary of Gardening. 1992.
Publication
 
Author
Huxley. A.
Publisher
MacMillan Press
Year
1992
ISBN
0-333-47494-5
Description
Excellent and very comprehensive, though it contains a number of silly mistakes. Readable yet also very detailed.
].
Plants will generally resprout if top growth is cut back by fire[
338
Title
IUCN Red List of Threatened Species
Publication
 
Author
 
Website
http://www.iucnredlist.org/
Publisher
 
Year
0
ISBN
 
Description
A list of plants under threat and facing possible extinction, usually with brief details of the threats and information on habitat.
].
Closely related to Juglans hindsii[
183
Title
Cornucopia - A Source Book of Edible Plants.
Publication
 
Author
Facciola. S.
Publisher
Kampong Publications
Year
1990
ISBN
0-9628087-0-9
Description
Excellent. Contains a very wide range of conventional and unconventional food plants (including tropical) and where they can be obtained (mainly N. American nurseries but also research institutes and a lot of other nurseries from around the world.
,
200
Title
The New RHS Dictionary of Gardening. 1992.
Publication
 
Author
Huxley. A.
Publisher
MacMillan Press
Year
1992
ISBN
0-333-47494-5
Description
Excellent and very comprehensive, though it contains a number of silly mistakes. Readable yet also very detailed.
]

Edible Uses

Seed - raw, cooked or used in pies, cakes, biscuits, confections etc[
183
Title
Cornucopia - A Source Book of Edible Plants.
Publication
 
Author
Facciola. S.
Publisher
Kampong Publications
Year
1990
ISBN
0-9628087-0-9
Description
Excellent. Contains a very wide range of conventional and unconventional food plants (including tropical) and where they can be obtained (mainly N. American nurseries but also research institutes and a lot of other nurseries from around the world.
]. A sweet flavour[
229
Title
The Complete Trees of N. America. Field Guide and Natural History.
Publication
 
Author
Elias. T.
Publisher
Van Nostrand Reinhold Co.
Year
1980
ISBN
0442238622
Description
A very good concise guide. Gives habitats, good descriptions, maps showing distribution and a few of the uses. It also includes the many shrubs that occasionally reach tree proportions.
]. The seed is small with a thick shell but it makes good eating and is said to have a better flavour than Juglans nigra[
183
Title
Cornucopia - A Source Book of Edible Plants.
Publication
 
Author
Facciola. S.
Publisher
Kampong Publications
Year
1990
ISBN
0-9628087-0-9
Description
Excellent. Contains a very wide range of conventional and unconventional food plants (including tropical) and where they can be obtained (mainly N. American nurseries but also research institutes and a lot of other nurseries from around the world.
]. The seed is up to 15mm in diameter[
229
Title
The Complete Trees of N. America. Field Guide and Natural History.
Publication
 
Author
Elias. T.
Publisher
Van Nostrand Reinhold Co.
Year
1980
ISBN
0442238622
Description
A very good concise guide. Gives habitats, good descriptions, maps showing distribution and a few of the uses. It also includes the many shrubs that occasionally reach tree proportions.
]. The seed ripens in late autumn and, when stored in its shell in a cool place, will keep for at least 6 months[
K
Title
Plants for a Future
Author
Ken Fern
Description
Notes from observations, tasting etc at Plants For A Future and on field trips.
].

An edible oil is obtained from the seed, it tends to go rancid quickly.

Medicinal

An infusion of the leaves is used to treat thin blood[
257
Title
Native American Ethnobotany
Publication
 
Author
Moerman. D.
Publisher
Timber Press. Oregon.
Year
1998
ISBN
0-88192-453-9
Description
Very comprehensive but terse guide to the native uses of plants. Excellent bibliography, fully referenced to each plant, giving a pathway to further information. Not for the casual reader.
].

Agroforestry Uses:

This species is sometimes used as a rootstock for the common walnut, Juglans regia[
183
Title
Cornucopia - A Source Book of Edible Plants.
Publication
 
Author
Facciola. S.
Publisher
Kampong Publications
Year
1990
ISBN
0-9628087-0-9
Description
Excellent. Contains a very wide range of conventional and unconventional food plants (including tropical) and where they can be obtained (mainly N. American nurseries but also research institutes and a lot of other nurseries from around the world.
].
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[
18
Title
Companion Plants.
Publication
 
Author
Philbrick H. and Gregg R. B.
Publisher
Watkins
Year
1979
ISBN
-
Description
Details of beneficial and antagonistic relationships between neighbouring plants.
,
20
Title
Companion Planting for Successful Gardening.
Publication
 
Author
Riotte. L.
Publisher
Garden Way, Vermont, USA.
Year
1978
ISBN
0-88266-064-0
Description
Fairly good.
,
159
Title
Wild Food Plants of Indiana.
Publication
 
Author
McPherson. A. and S.
Publisher
Indiana University Press
Year
1977
ISBN
0-253-28925-4
Description
A nice pocket guide to this region of America.
]. 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.)[
200
Title
The New RHS Dictionary of Gardening. 1992.
Publication
 
Author
Huxley. A.
Publisher
MacMillan Press
Year
1992
ISBN
0-333-47494-5
Description
Excellent and very comprehensive, though it contains a number of silly mistakes. Readable yet also very detailed.
].

Other Uses

Wood - moderately coarse-grained. An attractive wood, but the frequent branching pattern of the trunk limits the use of this wood commercially[
229
Title
The Complete Trees of N. America. Field Guide and Natural History.
Publication
 
Author
Elias. T.
Publisher
Van Nostrand Reinhold Co.
Year
1980
ISBN
0442238622
Description
A very good concise guide. Gives habitats, good descriptions, maps showing distribution and a few of the uses. It also includes the many shrubs that occasionally reach tree proportions.
]

Propagation

The seed is best sown as soon as it is ripe in individual deep pots in a cold frame[
80
Title
Hardy Woody Plants from Seed.
Publication
 
Author
McMillan-Browse. P.
Publisher
Grower Books
Year
1985
ISBN
0-901361-21-6
Description
Does not deal with many species but it is very comprehensive on those that it does cover. Not for casual reading.
]. 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[
78
Title
Propagation of Trees, Shrubs and Conifers.
Publication
 
Author
Sheat. W. G.
Publisher
MacMillan and Co
Year
1948
ISBN
-
Description
A bit dated but a good book on propagation techniques with specific details for a wide range of plants.
,
80
Title
Hardy Woody Plants from Seed.
Publication
 
Author
McMillan-Browse. P.
Publisher
Grower Books
Year
1985
ISBN
0-901361-21-6
Description
Does not deal with many species but it is very comprehensive on those that it does cover. Not for casual reading.
].
Cite as: Temperate Plants Database, Ken Fern. temperate.theferns.info. 2022-08-16. <temperate.theferns.info/plant/Juglans+californica>

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