Common Name: Hind's Black Walnut

General Information

Juglans hindsii is a deciduous tree that usually grows from 6 - 20 metres tall, occasionally more[, ]
The plant is harvested from the wild for local use as a food and source of materials. It has often been used as a rootstock for the common walnut (Juglans regia), is cultivated as a timber crop and is also often grown as an ornamental[].

Known Hazards

None known

Botanical References

, ,

Range

South-western N. America - California.

Habitat

Rocky and gravelly well-drained soils[], by the coast, along rivers and streams and occasionally to the slopes of Napa range[]

Properties

Edibility Rating
Other Uses Rating
Habit	Deciduous Tree
Height	15.00 m
Pollinators	Wind
Self-fertile	Yes
Cultivation Status	Cultivated, Ornamental, Wild

Cultivation Details

Juglams hindsii is not a very cold-hardy plant, being able to tolerate short periods with temperatures falling to around -5 to -8°c when fully dormant[]. It requires a hot summer if it is to thrive, in cool summers the wood does not fully ripen and is then more susceptible to damage by cold. The young growth in spring is also very tender and can be damaged by late frosts[].
Requires a deep well-drained loam and a sunny position sheltered from strong winds[, ]. Prefers a slightly alkaline soil[]. The plant's deep taproot gives the tree some degree of drought tolerance[].
This species is occasionally cultivated for its edible seed, and is also grown as a street tree[, ]. There are also some named forms that have been selected for their use as a rootstock[].
Plants produce a deep taproot and they are intolerant of root disturbance[, ]. 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[, ].
Flower initiation depends upon suitable conditions in the previous summer[]. 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[].
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[].
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.)[]. 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[].
This species is notably resistant to honey fungus[].

Edible Uses

Seed - raw[, , ]. The seed is small with a thick shell but it makes good eating[]. A sweet taste[, ]. The globose, downy fruits are 12 - 25mm wide; containing a thick-shelled, shallowly grooved nut[]
The globose fuits are 35 - 50cm in diameter, borne in groups of 1 - 2 with each containing a globose nut 24 - 32 mm in diameter[].

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

Medicinal

None known

Agroforestry Uses:

Species in this genus can produce chemicals which 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[, , ].
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.)[].

Other Uses

This species is often used in south-western N. America as a vigorous disease-resistant and drought tolerant rootstock for Juglans regia[, , ].
Juglans hindsii has been widely used as a rootstock for grafting Juglans regia and has been planted extensively in many parts of California for this purpose. It is now naturalized in many areas where it apparently did not occur before the introduction of commercial walnut growing. Possibly some of these naturalized populations are introgressed with Juglans nigra since spontaneous hybridization between Juglans hindsii and Juglans nigra has been reported in areas where both species have been planted. Currently most commercial walnut orchards use hybrid rootstocks, usually Juglans hindsii × Juglans regia[].

A black dye is obtained from the seed husks[].

The wood is heavy, hard, rather coarse grained[]. A valuable timber, the tree is occasionally cultivated for its wood[].

Propagation

The seed is best sown as soon as it is ripe in individual deep pots in a cold frame[]. 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[, ].