Of interest this week at Beal...

Honey locust Gleditsia triacanthos Family: the Bean family, the Fabaceae W. J. Beal Botanical Garden The honey locust, Gleditsia triacanthos, is a large shade tree native to the central United States west of a line extending from New Orleans to central Pennsylvania to the eastern thirds of Nebraska, Kansas, Oklahoma, and Texas. In most of its native range it develops large branched thorns, hence the species name, ‘triacanthos’ (three-parted thorns). Its Latin genus name, Gleditsia, is a tribute to the German botanist Johann Gottlieb Gleditsch. The author (Peter Carrington) wonders whether tribute is the right word, as Gleditsch was a prominent contemporary opponent of Linnaeus, who assigned the name (was this an editorial comment about ‘thorniness’. . .) Almost all modern plantings, consist of the thornless variety, inermis, that occurs naturally, or can be cloned from the thornless upper branches of thorn-bearing specimens.

In North America, as well as in many temperate nations abroad, honey locust is an ubiquitous street tree, though suffering from many diseases and pests, including mimosa webworm, Homadaula anisocentra, and the honey locust plant bug, Diaphnocoris chlorionis.

Of interest is the honey locust habit of having both singly pinnately compound leaves (above photos; middle), doubly pinnate leaves (above photos; right), and intermediate leaves (above photos; middle right) on the same plant.

Gleditsia flowers are small and located on inconspicuous hanging spikes. Honey locust is polygmo-dioecious, meaning each tree is predominantly male or female, but with a few flowers of the opposite sex occurring on most specimens.

The combination of sweet edible large pods and large thorns recalls the similar adaptations of the African umbrella acacias (e.g. Acacia tortilis) thought to have developed in response to sharing habitat with elephants. Connie Barlow, in her book, The Ghosts of Evolution, Nonsensical Fruit, Missing Partners, and Other Ecological Anachronisms, New York, Basic Books, 2000, points out that North America had tree browsing elephants, mastodons, until 13,000 years ago. The pods are presently The Latin species epithet of honey locust, ‘triacanthos’ means three-parted thorns. Young thorns may be three-parted, but they can develop into huge branched thorn complexes (below). Safer thornless types (var. inermis) dominate in plantings and yards.

grown as forage for stock and the unripe pods can be consumed by people as well, as long as they are not confused with toxic pods of black locust, Robinia pseudoacacia, or Kentucky coffee tree, Gymnocladus dioicus.

The pods were used medicinally in the Cherokee nation to treat dysentery and measles, though in Creek villages, boiled branches were tried against smallpox and measles. Several indigenous communities made cough medicine from the bark and roots.