Practical
Plants

Carya californica

California Walnut

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

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Taxonomy and growth

Genus
Carya
Life cycle
perennial
Foliage
deciduous
Woodiness
woody
Height
9 m
Fertility
self fertile
Flower type
monoecious
Pollinators
Wind

Uses

Edible uses

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

Seed - raw or cooked. Sweet but with a thick shell, the seed is said to have a better flavour than Juglans nigra. It is also used in cakes, pies, biscuits etc[3]. The seed ripens in late autumn and, when stored in its shell in a cool place, will keep for at least 6 months[K].

Plant part
Seed

Material uses

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

This species is sometimes used as a rootstock for the common walnut, Juglans regia[3].

Ecology and functions

Ecosystem niche
Canopy, Secondary canopy

Rootstock

Environment

Range
South-western N. America.
Habitat
Not known
Light
full sun
Shade tolerance
light shade
Water
moderate
Hardiness
Zone 8+
Soil textures
sandy, loamy, clay
Soil pH
acid, neutral, alkaline
Tolerates Nutritionally Poor Soil
No
Drought
intolerant

Propagation

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

Seed - requires a period of cold stratification. It is best sown in a cold frame as soon as it is ripe[7]. Stored seed should be kept moist (but not wet) prior to sowing and should be sown in a cold frame as soon as possible[7]. Where possible, sow 1 or 2 seeds only in each deep pot and thin to the best seedling. If you need to transplant the seedlings, then do this as soon as they are large enough to handle, once more using deep pots to accommodate the tap root. Put the plants into their permanent positions as soon as possible, preferably in their first summer, and give them some protection from the cold for at least the first winter[78, K]. Seed can also be sown in situ so long as protection is given from mice etc and the seed is given some protection from cold[4] (a plastic bottle with the top and bottom removed and a wire mesh top fitted to keep the mice out is ideal)

Cultivation

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

Prefers a deep moisture-retentive loam in a sunny sheltered position, requiring a good summer for best development[1][6][2][4]. Slow growing[4]. This species is not hardy in the colder areas of the country, it tolerates temperatures down to between -5 and -10°c[4]. Plants are strongly tap-rooted and should be planted in their permanent positions as soon as possible[1][2]. Sowing in situ would be the best method so long as the seed could be protected from mice[1][4]. Trees are late coming into leaf (usually late May to June) and lose their leaves early in the autumn (usually in October)[2]. During this time they cast a heavy shade. These factors combine to make the trees eminently suitable for a mixed woodland planting with shrubs and other trees beneath them[2]. Plants in this genus are notably resistant to honey fungus[4]. Most species in this genus have quite a wide range of distribution and, in order to find trees more suited to this country, seed from the most appropriate provenances should be sought[2]. Most trees growing in Britain at present tend to only produce good seed after hot summers[2]. This species is closely related to J. hindsii. Trees are self-fertile but larger crops of better quality seeds are produced if cross-pollination takes place[5].

References

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

    ↩1↩2↩3

  2. ? The Plantsman. Vol. 9. 1986 - 1987. Royal Horticultural Society 1986-00-00

    ↩1↩2↩3↩4↩5↩6

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

    ↩1↩2

  4. 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

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

    ↩

  6. Howes. F. N. Nuts. Faber 1948-00-00

    ↩

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

    ↩1↩2

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