The honey locust tree, Gleditsia triacanthos, is an attractive deciduous tree from North America, introduced to this country at the beginning of the 18th century. It has small pinnate leaves and curious banana-shaped pods which turn dark brown when ripe in the autumn. The bark is a purplish grey with distinct ridges. It has become a popular ornamental tree in warmer parts of the United Kingdom. But, thanks to its rapid growth and tolerance of poor conditions, it is now regarded as a major invasive environmental and economic weed in parts of the USA and in agricultural regions of Australia.
The word “honey” in its English name derives from the edible pulp inside pods, long used by the Cherokee to make beverages.
Trees found in the wild have vicious-looking spines - “triacanthos” means “three-spined”. It has been suggested that these evolved as protection against larger grazing animals. Most of the specimens planted in parks and streets are Gleditsia triacanthos var. inermis, a thornless cultivar, but there are several trees with spines at the north-eastern end of Albrighton Road (off Dog Kennel Hill) and another one in Idmiston Road, close to the junction with Chancellor Grove.
There are several examples in Dulwich Park. At least one, at the east end of the Park north of Rosebery Gate, appears to be the ‘Sunburst’ variety with bright golden leaves in spring. To the north of Dulwich, there is an attractive avenue of young trees along the Walworth Road.
There is a mature Gleditsia just outside the Dulwich Estate offices near the statue of Edward Alleyn. Nearby, a younger specimen in the garden of Dulwich Picture Gallery commemorates Stella Benwell (1920-2013), chair of the Dulwich Society Tree Committee from 1985 to 2008.