''Juglans hindsii'', commonly called the Northern California black walnut and Hinds's black walnut, is a species of

walnut tree Walnut trees are any species of tree in the plant genus ''Juglans'', the type genus of the family (biology), family Juglandaceae, the seeds of which are referred to as walnuts. All species are deciduous trees, tall, with pinnate leaves , with ...

native to the western United States (California and Oregon). Jepson Herbarium (2013): ''Juglans hindsii''
/ref> It is commonly called claro walnut by the lumber industry and woodworkers, and is the subject of some confusion over its being used as

rootstock A rootstock is part of a plant, often an underground part, from which new above-ground growth can be produced. It could also be described as a stem with a well developed root system, to which a bud from another plant is grafted. It can refer to ...

for

English walnut ''Juglans regia'', known by various common names including the common walnut, English walnut, or Persian walnut amongst other names, is a species of Juglans, walnut. It is native to Eurasia in at least southwest and central Asia and southeast ...

Description

''Juglans hindsii'' is a large tree that grows up to tall and may reach over with enough shade. The species normally has a single erect trunk, commonly without branches in the lower half of the tree, and a crown that can be wider than the tree is tall. Trunks may reach in diameter near the base of the tree. The

leaf A leaf (: leaves) is a principal appendage of the plant stem, stem of a vascular plant, usually borne laterally above ground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leav ...

is approximately long, with 13–21 leaflets per leaf, each long, with dentate margins. The vein axils bear tufts of hair underneath, differentiating the species from the Southern California walnut. The species is

monoecious Monoecy (; adj. monoecious ) is a sexual system in seed plants where separate male and female cones or flowers are present on the same plant. It is a monomorphic sexual system comparable with gynomonoecy, andromonoecy and trimonoecy, and contras ...

, with male flowers in yellow-green catkins up to long and females stemming from young twigs in groups of 1–3. The nut is up to across, with a smooth, brown, thick shell.

Taxonomy

The current classification of the plant is as a distinct species. Some botanists and the 1993 edition of '' The Jepson Manual'' had classified it as ''Juglans californica'' subsp. ''hindsii'', a

subspecies In Taxonomy (biology), biological classification, subspecies (: subspecies) is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (Morphology (biology), morpholog ...

of ''

Juglans californica ''Juglans californica'', the California black walnut, also called the California walnut, or the Southern California black walnut, is a large shrub or small tree (about ) of the walnut family, Juglandaceae, endemic to the Central Valley and the Co ...

'' (Southern California black walnut).

Distribution and habitat

The historical range of ''J. hindsii'' is from the

San Joaquin Valley The San Joaquin Valley ( ; Spanish language in California, Spanish: ''Valle de San Joaquín'') is the southern half of California's Central Valley (California), Central Valley. Famed as a major breadbasket, the San Joaquin Valley is an importa ...

and

Sacramento Valley The Sacramento Valley is the area of the Central Valley of the U.S. state of California that lies north of the Sacramento–San Joaquin River Delta and is drained by the Sacramento River. It encompasses all or parts of ten Northern California ...

to the inner northern

California Coast Ranges The Coast Ranges of California span from Del Norte County, California, Del Norte or Humboldt County, California, south to Santa Barbara County, California, Santa Barbara County. The other three coastal California mountain ranges are the Trans ...

and

San Francisco Bay Area The San Francisco Bay Area, commonly known as the Bay Area, is a List of regions of California, region of California surrounding and including San Francisco Bay, and anchored by the cities of Oakland, San Francisco, and San Jose, California, S ...

, in

Northern California Northern California (commonly shortened to NorCal) is a geocultural region that comprises the northern portion of the U.S. state of California, spanning the northernmost 48 of the state's List of counties in California, 58 counties. Northern Ca ...

. A 2020

IUCN The International Union for Conservation of Nature (IUCN) is an international organization working in the field of nature conservation and sustainable use of natural resources. Founded in 1948, IUCN has become the global authority on the status ...

assessment has extended this range: north to Oregon and south to Southern California, in areas of similar habitat type. The northernmost pre-colonial ''J. hindsii'' tree was located in

Douglas County, Oregon Douglas County is one of the List of counties in Oregon, 36 counties in the U.S. state of Oregon. As of the 2020 United States census, 2020 census, the population was 111,201. The county seat is Roseburg, Oregon, Roseburg. Oregon Geographic ...

, before it was blown over in November 2017. A ring count determined the tree predated the arrival of settlers by approximately 100 years. The Native Plant Society of Oregon has also documented multiple trees of pre-colonial age in Oregon's Rogue Valley. The tree grows in

riparian A riparian zone or riparian area is the interface between land and a river or stream. In some regions, the terms riparian woodland, riparian forest, riparian buffer zone, riparian corridor, and riparian strip are used to characterize a ripar ...

woodlands, either in mono-species stands, or mixed with California oak species (''

Quercus An oak is a hardwood tree or shrub in the genus ''Quercus'' of the beech family. They have spirally arranged leaves, often with lobed edges, and a nut called an acorn, borne within a cup. The genus is widely distributed in the Northern Hemisp ...

'' spp.) and Fremont cottonwood (''Populus fremontii'') trees.

Conservation

''Juglans hindsii'' was formerly assessed as Seriously Endangered on the California Native Plant Society Rare Plant Inventory. In a 2019 revision, the species was upgraded to common. It is threatened by hybridization with orchard trees, urbanization, and habitat conversion to agriculture.

Cultivation

''Juglans hindsii'' has been commercially important as a

for orchard stock of '' J. regia'' (English walnut) trees all over the world. It is also used as a parent to the fast-growing Luther Burbank hybrid rootstock, commonly called "Paradox" (''Juglans hindsii'' x ''Juglans regia''). The Northern California walnut is cultivated by specialty California native

plant nurseries A nursery is a place where plants are propagated and grown to a desired size. Mostly the plants concerned are for gardening, forestry, or conservation biology, rather than agriculture. They include retail nurseries, which sell to the general ...

. It is used as an

ornamental tree Ornamental plants or ''garden plants'' are plants that are primarily grown for their beauty but also for qualities such as scent or how they shape physical space. Many flowering plants and garden varieties tend to be specially bred cultivars th ...

in traditional and

wildlife garden A wildlife garden (or habitat garden or backyard restoration) is an Biophysical environment, environment created with the purpose to serve as a sustainable haven for surrounding wildlife. Wildlife gardens contain a variety of habitats that cater t ...

s, and for

habitat garden A wildlife garden (or habitat garden or backyard restoration) is an environment created with the purpose to serve as a sustainable haven for surrounding wildlife. Wildlife gardens contain a variety of habitats that cater to native and local plan ...

natural landscaping Natural landscaping, also called native gardening, is the use of native plants including trees, shrubs, groundcover, and grasses which are local to the geographic area of the garden. Benefits Maintenance Natural landscaping is adapted to t ...

projects, and climate compatible drought-tolerant gardens. The tree is also planted in

habitat restoration Ecological restoration, or ecosystem restoration, is the process of assisting the recovery of an ecosystem that has been degraded, damaged, destroyed or transformed. It is distinct from conservation in that it attempts to retroactively repair ...

projects.

Pests

''Juglans hindsii'' is infested by ''

Rhagoletis juglandis ''Rhagoletis juglandis'', also known as the walnut husk fly, is a species of tephritid or fruit fly in the family Tephritidae. It is closely related to the walnut husk maggot ''Rhagoletis suavis'' (Loew, 1862). This species of fly belongs to the ...

'', commonly known as the walnut husk fly, which lays its eggs in the husks of walnut fruit. ''R. juglandis'' infests other varieties of walnut trees as well, such as ''J. regia'' (the English or Persian walnut), ''J. rupestris'' (native to Arizona and Texas), and ''J. hindsii'' (the California black walnut).

Allergenicity

It is a severe

allergen An allergen is an otherwise harmless substance that triggers an allergic reaction in sensitive individuals by stimulating an immune response. In technical terms, an allergen is an antigen that is capable of stimulating a type-I hypersensitivi ...

. Pollination typically occurs in spring.

Uses

The nut is edible. The wood of ''J. hindsii'' is commonly called ''claro walnut'' by the lumber industry and woodworkers. It is highly figured with a rich brown color and striking grain patterns, especially in the crotch areas, where large limbs meet the trunk. It is used in small quantities to make fine furniture and gun stocks, and sold as slabs to make large natural-top tables because of its durability, good working properties, and swirling iridescent figure. Some confusion exists about the nature of claro walnut because ''J. hindsii'' is commonly used as the rootstock of orchard trees. The section below the original graft is claro walnut wood, while the section above is the lighter-colored English walnut. Some woodworkers take advantage of this by making the color change a feature of their work.Mcfaddenfurniture.com: 'armoire'
/ref>

References

*"Some preliminary observations on the California black walnut (''Juglans californica'')" — Anderson, E. N.; ''Fremontia: A Journal of the California Native Plant Society''. January 2002.

External links

* *
Jepson Flora Project: ''Juglans hindsii''

Calflora Database: Juglans hindsii'' (Northern California black walnut)

Virginia Tech tree ID: Hind's black walnut (''Juglans hindsii'')

''Juglans hindsii'' — U.C. Photo gallery
{{Taxonbar, from=Q291739 hindsii Trees of Northern America Natural history of the California chaparral and woodlands Natural history of the California Coast Ranges Natural history of the Central Valley (California) Trees of Mediterranean climate Edible nuts and seeds Plants used in Native American cuisine Pre-Columbian California cuisine Garden plants of North America Drought-tolerant trees Ornamental trees Plants described in 1909