Aesculus Dallimorei - Dallimore horse-chestnut

Aesculus Dallimorei, commonly known as Dallimore's Horse Chestnut, is a rare ornamental tree in cultivation, sought after for its beautiful spring flowers, wide crown, and attractive palmate foliage. This tree is a graft chimera rather than a hybrid, combining the characteristics of the Horse Chestnut with those of the American Yellow Buckeye, Aesculus flava. It will make a unique addition to the garden of a rare plant enthusiast.

Aesculus Dallimorei, also known as Aesculus + dallimorei, is a chimera resulting from the grafting of tissues from Aesculus hippocastanum (the Horse Chestnut) and A. flava (the Yellow Buckeye), or sometimes A. pavia (the Red Buckeye), according to sources. William Dallimore observed that a yellow buckeye growing near his house in Bidborough, Kent, bore a branch that, with its leaves and flowers, resembled the common Horse Chestnut; the tree was grafted and the branch in question was born from the union of a rootstock and a scion. This botanical curiosity was described in 1956. This horse chestnut belongs, like its parents, to the family Hippocastanaceae.

Dallimore's Horse Chestnut can reach a height of 6 to 10 m, forming a short trunk and a dense, spherical crown that will spread 4 to 6 m wide. Its deciduous foliage is composed of 5 to 7 palmate leaflets, arranged in a fan shape, and measuring between 15 and 30 centimetres long. The leaves do not exactly resemble those of each parent plant, particularly due to the shape of the leaflets. The leaflets are broadly elliptical and pointed, slightly wrinkled, dark green on the upper side, with a white down on the underside. In autumn, they turn yellow-brown before falling. Flowering occurs in May-June. The flower colour can vary depending on sources and clones, ranging from creamy white with a red spot at the base to red, pink, or orange. Individually, the flowers have four petals arranged in two different pairs, with the lower pair shorter but wider than the upper pair. In the Horse Chestnut, the petals number five and are all the same size. They appear in upright panicles of 20-25 cm and are highly attractive to pollinating insects. This tree is sterile and generally does not produce viable fruits.

Aesculus Dallimorei is a collectible tree that deserves to be showcased in a large garden. This horse chestnut is hardy (-20°C) and easy to grow in loose, well-drained garden soil that is not too dry. In the garden, it can be used as a specimen tree, planted in groups to create a screen or hedge, or integrated into a large grove, with a Japanese Flowering Dogwood (Cornus kousa) or a Golden Rain Tree (Koelreuteria paniculata), for example.