Xanthoceras sorbifolium

Xanthoceras sorbifolium, also known as Shinyleaf Yellowhorn, is a shrub that is very rare in our gardens, probably due to its slow growth, the fragility of the young plants, and limited ability to propagate. It is a charming cousin of the Chinese Goldenrain Tree (Koelreuteria paniculata) that has light foliage reminiscent of the mountain ash, offers abundant and colourful spring flowering, and beautiful autumn colours. It is also an interesting plant for its edible seeds. Once mature, this shrub becomes very resistant to cold, as well as summer drought. It undoubtedly deserves a place in many gardens!

The Xanthoceras genus belongs to the Sapindaceae family and has only one species, Xanthoceras sorbifolium, native to northern China and also found in Korea in its natural state. It was introduced to France as early as 1866 but remains rarely cultivated there. It is rarely found except in urban parks or botanical gardens, such as the Paris botanic garden where a beautiful specimen can be admired. Very resistant to cold once mature, the shrub tolerates limestone soils if they are deep and well-drained, as well as summer drought once well rooted. Overall, it only fears excessively wet soils and summers that are both hot and humid.

It is a large shrub or small slow-growing tree, with a bushy habit, reaching an average height of 3.5 m (11 ft) to 4 m (13 ft) and almost the same width when fully grown. It forms a single trunk or several trunks and has a spreading, sparsely branched crown. Its bark is dark brown and cracks with age. The deciduous foliage is composed of pinnate leaves that are 12 to 30 cm (5 to 12 in) long, divided into 15 to 19 elliptical and toothed leaflets, with the terminal leaflets often trilobed. The young shoots are acid-green in colour; the leaves then become bright green in summer and golden-yellow in autumn before falling off. In winter, the branches are bare. The flowering period is from April to June depending on the region; this is abundant and lasts for 4 to 6 weeks. The plant produces inflorescences that contain only male flowers as well as inflorescences composed of bisexual flowers. The bisexual inflorescences are produced at the end of the branches, while the upright male inflorescences form lower down on the branches. Each conical panicle measures 15 to 25 cm (6 to 10 in) long. It consists of numerous campanulate flowers with 5 petals, 2 cm (1 in) in diameter; these are slightly fragrant and greatly appreciated by bees. The petals are white, while the flower throat gradually changes from green to acid-yellow, orange, and dark reddish-purple. After pollination, the flowers give rise to spherical capsules, 5-6 cm (2 in) in diameter, ripening in September. Each capsule, divided into 3 chambers, opens to release 6 to 18 large round, black, shiny, edible seeds, rich in oil, with a taste reminiscent of macadamia nuts.

Xanthoceras sorbifolium is an original ornamental shrub to be planted alone in a small garden or within a bed. It can be paired with other lesser-known flowering shrubs to create a unique scene that will surprise your visitors, such as Clerodendron trichotomum, with its large dark green leaves that contrast with the delicate foliage of Xanthoceras, while its late flowering takes over before surprising with its unique decorative fruits. Another rare and slow-growing shrub that can find its place alongside Xanthoceras is Garrya elliptica, with its evergreen foliage consisting of small, fairly dark green and slightly glossy leaves, which will contrast with the vibrant green of Xanthoceras. But above all, when Xanthoceras loses its leaves, Garrya will enchant the winter with its long catkins hanging from its branches like pendants on a chandelier.

An exceptional shrub: in China, Xanthoceras sorbifolium is used to vegetate barren mountains and fight desertification. Its roots help stabilise the soil and limit erosion.