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Tree of the month: Common Horsechestnut

Horsechestnut flowers.

Common Horsechestnut

Latin Name: Aesculus hippocastanum

Locations: A week ago common horsechestnut trees were in full bloom in various parts of the Island. Some stood out along Smith Street and a large specimen commanded attention in front of Havens House.

Tree stats: Native to Southeastern Europe, common horsechestnut usually grows 50 to 75 feet in cultivation. In spring, the trees are impossible to miss with their upright spires of white flowers stained with blotches of pink and yellow. The large, dark leaves hang gracefully from the branches like tree hands composed of five to seven leaflets. The flowers are followed by prickly fruit, which contain one or two brown, shiny seeds. In the fall, the leaves can turn a handsome yellow.

Landscape uses: Horsechestnuts are impressive roadside and landscape trees if given room to grow properly. The Havens tree was planted too close to a tuliptree (or visa versa), repressing the potential width of both. The horsechestnut tree’s one downside is a tendency for the leaves to scorch or turn brown during the summer. Fungicide may be applied when the leaves emerge, although this strategy is limited to smaller trees.

A word of caution: Common horsechestnut seeds look similar to those of the sweet chestnut (Castanea sativa). However, the former is toxic to humans while the latter has been a nutritious and delicious food staple for centuries. 

Horsechestnut at the corner of Oxford and New York avenues.

Think pink: While common horsechestnut flowers are glorious, the flowers of Aesculus X carnea, a hybrid between Aesculus hippocastanum and the native red buckeye (Aesculus pavia), are a striking deep pink. Small groups of these hybrids, planted by Friends of Trees a decade ago, can be seen on Menantic and Manhanset roads. The red buckeye is worth growing for its stunning red flowers. Unlike the horsechestnut, it needs understory shade and moist soil. 

Bonkers for Conkers: Though horsechestnut seeds are inedible, they were once used as a cure for horse ailments, thus the tree’s common name. The seeds are more amusingly used for the time-honored British game of Conkers. Each player has a horsechestnut seed (known as a conker) that has been threaded with string. The player who smashes an opponent’s seed first is declared the winner. No longer just a children’s pastime, competitive tournaments have become popular in Britain and America. Book your trip now for the annual North American Conker Championship that takes place on October 19th in Annapolis Royal, Nova Scotia. As a demonstration of the organization’s semi-seriousness, its site lists sixteen “Rules of Engagement for the Noble Game of Conkers.” (Sample rule: “A distance of no less than 8″ or 20cm of lace must be between knuckle and conker.”) Sounds like this could be a fun, fall event on Shelter Island. 

Tim Purtell

President, Shelter Island Friends of Trees

[email protected]