Walnuts Tree
Walnut family (Juglandaceae)
Some 15 to 20 species of walnut are found throughout the world, in North and South America, in south eastern Europe, and in south eastern Asia. Conservatively there are four species native to North America; some authorities treat a variety north America ; some authorities treat a variety of California black walnut (juglans California var. hindsii) and a variety of Arizona walnut (juglans elaeopyren var. microcarpa ) as separate species. The North American species are usually found mixed with other hardwoods, but depending on the species may be found in small pure stands. They typically prefer moist, rich soil, but are variably adaptable to drier soils, and are not particularly shade-tolerant. The walnuts are generally fast growing and range from short-to long-lived.
Ranging from small to large trees, depending on the species, walnuts tend to be relatively short trunked with large rounded crowns of stout branches and pinnately compound leaves. The twigs have characteristic chambered piths. Leaves are alternately arranged and have from 5 to 21 elliptical leaflets, depending on the species. The flowers of walnuts are characteristically tiny and without petals, male and female flowers gathered into unisexual clusters on the same tree, opening as the leaves are emerging. Numerous male flowers are borne in pendulous spikes from lateral buds near the tips so twigs, while female flowers are borne single, or in twos or threes at the ends of twigs. Female flowers characteristically have two well-develops from the female flower is a large, edible hard-shelled nut surrounded by a somewhat fleshy that does not split open, but turns brown and gradually tots away. Walnuts generally have well-developed deep root systems.
Walnuts are probably best known for their edible nuts, and in some species for the oil that can be extracted from them. None of the native species are commercially grown for their nuts, however. Production in mainly confined to local collecting. In addition, the native species are sometimes planted as shade trees. However, walnuts produce a chemical that inhibits the growth of many plants within the reach of their roots, and consideration of this should be made before planting any of them. Black walnut wood is highly esteemed and is commercially important, but that of the other species is much less valued. The nuts are an important food source for wildlife and the trees provide shelter. Their root systems make them useful also in stabilizing soils prone to erosion.
California Black Walnut
California walnut is endemic to California in scattered locations between ventura and San Diego Counties. A northern California subspecies, J. californica ‘hindsii,’ is sometimes treated as a separate species. Due to urbanization and livestock grazing, its natural range is declining, with the extensive stands on north-facing slopes in the Puente and San Jose Hills of eastern Los Angeles County. It is found in relatively pure stands, or mixed with coast live oak, occasionally in chaparral communities or coastal sage scrub, where climates are Mediterranean. California black walnut prefers moist, deep, alluvial soils, especially clays, no north-facing slopes, creek beds, and canyon bottoms. It is frequently subjected to fire, and has adapted to sucker from the root crown and trunk.
A relatively short-lived tree, California black walnut is variable in form depending on age, site conditions and fire damage. In dense stands it is usually single-trunked to 50 ft. (15 m), but in more open settings prone to fire it usually attains only half that, and is multitrunked supporting a broad, open crown. The black-brown bark becomes furrowed with age and is strongly scented. Leaves are typically walnut like but small, to 3in. (7.5 cm) long, mid-green and aromatic when bruised. Flowers are also borne in the walnut fashion, and the walnut fruit is globose and not usually produced in dry years, California black walnut tends toward having a deep top root.
California black walnut is widely planted in urban forestry projects, and makes a handsome small to medium-sized ornamental tree. It has also been used to control erosion on steep road embankments where the soil is deep. The nuts are edible, but not grown commercially. Many rodents eat the nuts, and dense stands provide shelter for an abundance of bird species and small mammals. California black walnut is prone to both crown rot and heart rot; the latter renders the tree susceptible to termites and wood-boring beetles.
Butternut, white walnut
Butternut ranges from southwest New Brunswick, south to extreme northern Georgia, west to Arkansas, north to eastern Minnesota and northwest to southern Quebec. Throughout its range it is uncommon and is in decline in many areas due to butternut canker, a fungal disease. It is found as a canopy tree with other hardwoods and conifers, and is only partially shade-tolerant as a seeding, butternut prefers deep, moist soils over limestone with good drainage, and is usually found in valleys above the floodplain, and on slopes.
Butternut reaches 70 ft. (21 m) on a short single trunk, bearing a high, broad, open crown of stout branches. It grows bark ages form smooth to tough and furrowed. Leaves are typically walnut like, aromatic when bruised, to 24 in. (60 cm) long, with up to 17 leaflets, yellow-green above, paler and softly hairy beneath, turning yellow-brown in autumn. Flowers are borne in typical walnut fashion, the females in clusters of up to eight. The walnuts like fruits are clustered, and individually large, egg shaped, and thick-husked, with sticky rust-colored hairs; they are borne heavily in alternate years. The nut inside contains an aromatic, oily seed. Occasionally tap-tooted on deep soils, butternut usually forms deeply penetrating lateral roots.
Butternut wood is soft and not much used commercially, except for small utensils and interior finishes. The seed is highly palatable, and a number of varieties are cultivated for the nutmeat and its oil. The nut is an essential ingredient in maple butternut candy in New England, and the oil was used by Native peoples for consumption and ritual anointing. The husk yields on orange or yellow dye. Butternut it occasionally found as a shade tree in parks, but it is not commonly planted as an ornamental. The nut is consumed by squirrels and other rodents, and deer will eat the follage.
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