Tree of the Month: Aesculus × carnea ‘Briotii’

The horse chestnut—who hasn’t played with its fruit as a child in autumn? Making a spider web with a few wooden sticks and a ball of yarn is a true classic. In landscape architecture, horse chestnuts are often used to bring monumentality to avenues and parks. They also play an important ecological role as a source of food.

Origin and Identification

Aesculus × carnea ‘Briotii’ is a deciduous tree belonging to the Sapindaceae family. Commonly known as the red horse chestnut, it is a hybrid between Aesculus hippocastanum and Aesculus pavia. Little is known about the very first crossing of these species, but the nearly identical cultivar ‘Briotii’ was selected in 1858 in Trianon, France. Aesculus × carnea ‘Briotii’ combines the crown form and leaves of Aesculus hippocastanum with the vibrant flowers of Aesculus pavia.

A remarkable feature of horse chestnuts is their exceptionally large winter buds, which contain folded leaves and pre-formed flowers. When they unfold, the display is spectacular. Because the young fresh shoots already include the flower, horse chestnut branches are often used as cut greenery in flower shops during spring.

This tree species can grow 10 to 15 meters tall and has a dense canopy with a rounded crown spreading 10 to 15 meters wide. The ‘Briotii’ cultivar has a more oval crown shape, making it especially suitable as an avenue tree. The leaves are large, palmate-compound, usually consisting of five to seven leaflets with a glossy dark green color. In addition to its fruit—similar to the sweet chestnut but with few spines on the husk—the leaf scars are shaped like horseshoes, complete with nail marks. This feature explains the name “horse chestnut.”

Added Value for the Ecosystem

Aesculus × carnea ‘Briotii’ is renowned for its spectacular flowers, bright red and appearing in large clusters in late spring. Their striking color gives the tree high ornamental value in gardens and parks, and red flowers are a rarity in nature. They also bloom at a time when bumblebees and bees are abundant. Standing under the tree in bloom, you’ll hear the constant buzzing of hungry insects.

In winter, bullfinches particularly value the large buds, pecking them open to eat the contents. The peeling bark also offers winter shelter for insects. Like other members of the Sapindaceae family, the horse chestnut thus plays an important role in the ecosystem. In autumn, the tree produces small, spiny fruits containing one or two seeds. While the fruit is inedible for humans, it provides food for wildlife such as wild boar, squirrels, and birds.

Application and Use

The red horse chestnut is a beautiful and valuable species, appreciated above all for its abundant flowers. Historically, landscape architects have used horse chestnuts to create monumentality in parks, large gardens, and avenues.