Black locust

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Black Locust

Flowers

Scientific classification

Kingdom:	Plantae
Division:	Magnoliophyta
Class:	Magnoliopsida
Order:	Fabales
Family:	Fabaceae
Subfamily:	Faboideae
Tribe:	Robinieae
Genus:	Robinia
Species:	R. pseudoacacia

Binomial name

Robinia pseudoacacia
L.

Black Locust (Robinia pseudoacacia) is a tree in the subfamily Faboideae of the pea family Fabaceae. It is native to the southeastern United States, but has been widely planted and naturalized elsewhere in temperate North America, Europe and Asia and is considered an invasive species in some areas. A less frequently used common name is False Acacia, which is a literal translation of the specific epithet.

It grows to 14–25 m tall, with a trunk up to 0.8 m diameter (exceptionally up to 27 m tall and 1.6 m diameter in very old trees), with thick, deeply furrowed blackish bark. The leaves are 10–25 cm long, pinnate with 9–19 oval leaflets, 2–5 cm long and 1.5–3 cm broad. Each leaf usually has a pair of short thorns at the base, 1–2 mm long or absent on adult crown shoots, up to 2 cm long on vigorous young plants. The intensely fragrant flowers are white, borne in pendulous racemes 8–20 cm long, and are considered edible. The fruit is a legume 5–10 cm long, containing 4–10 seeds.

Although similar in general appearance to Honey locust, it lacks that tree's characteristic long branched spines on the trunk, instead having the pairs of short thorns at the base of each leaf; the leaflets are also much broader.

As with honey locust, black locust reproduces through distinct hanging pods but they are smaller, lighter, and easily carried long distances by the wind. Unlike honey locust, but like the related European Laburnum, the pods are toxic. In fact, every part of the tree, especially the bark, except the flowers is considered toxic. However, various reports have been suggested that the seeds and the young pods of the black locust are considered to be edible when cooked, since that the poisons that are contained in this plant are completely destroyed by heat.

Black locust has nitrogen-fixing bacteria on its root system; for this reason it can grow on poor soils and is an early colonizer of disturbed areas.

[edit] Cultivation and uses

Black locust is a major honey plant in eastern USA, and, having been taken and planted in France, is the source of the renowned acacia monofloral honey from France. Flowering starts after 140 growing degree days.

In Europe it is often planted alongside streets and in parks, especially in large cities, because it tolerates pollution well. The species is unsuitable for small gardens due to its large size and rapid growth, but the cultivar 'Frisia', a selection with bright yellow-green leaves, is occasionally planted as an ornamental tree.

The wood is extremely hard, resistant to rot and long lasting, making it prized for fence posts and small watercraft. As a young man, Abraham Lincoln spent a lot of time splitting rails and fence posts from black locust logs. In the Netherlands and some other parts of Europe, black locust is the most rot-resistant local tree, and projects have started to limit the use of tropical wood by promoting this tree and creating plantations.

Black Locust is unsurpassed as firewood for wood stoves; it burns slowly, with little visible flame or smoke, and has a higher heat content than any other wood that grows in the Eastern US, comparable to the heat content of anthracite".^[1]. However, for this use it should be split when green, then dried for 2 to 3 years, and ignited by insertion into a stove already hot from burning of a load of some other hardwood.^{[citation needed]} In fireplaces it is less satisfactory because knots and beetle damage in black locust make the wood prone to "spitting" coals for distances of up to several feet.^{[citation needed]}