Betula ermanii Mount Zao Purple - Erman's Birch

Betula ermanii 'Mount Zao Purple' is a very rare Japanese variety, sought after for its original purple-chocolate bark, covered with cream-orange stripes that exfoliate and widely striped with prominent horizontal cream lenticels! It forms a medium-sized deciduous tree with a slender, upright, branching silhouette often from the base, highlighting its highly marbled bark. The medium green deciduous foliage turns to rich orange tones in autumn before falling. This hardy tree grows in sunny well-drained soils but prefers moist soils. Plant it isolated on a lawn or in front of a large grove or curtain of dark or even bluish foliage trees to bring out the vibrant colours of its bark.

The Erman Birch, commonly known as the Erman Birch, is a deciduous tree native to mixed forests in Northeast Asia. The habit of this species, which reaches up to 25 m in height in its natural habitat, is columnar to oval, rounding with age. The 'Mount Zao Purple' variety was obtained from seeds collected by Kenneth Ashburner on Mount Zao, north of Honshu, Japan.

In our climate, the Erman Birch 'Mount Zao Purple' will reach approximately 15 m high and spread over 10 m after many years. In 20 years, it will only reach about 8 m high and 4 m wide. Its semi-open crown consists of loose branches covered with purple bark with chocolate tones. Its rather upright and oval shape is spreading and rounding with age. The bark is horizontally streaked with long cream lenticel bands and exfoliates in long orange cream flakes. Its ovate to triangular, 4 to 10 cm long, slightly toothed leaves are medium green. They bud early in spring and turn to deep orange early in autumn. The male and female inflorescences appear at the same time as the leaves in the form of pendulous yellow-green catkins. The flowers are very nectar-rich. The root system of this tree is quite shallow, dense, and composed of secondary roots bearing numerous rootlets. It is better to keep this beautiful birch away from the house, as strong winds could potentially uproot it, especially when it is in full leaf and the soil is very moist.

Betula ermanii 'Mount Zao Purple' is a very tolerant species in terms of soil, as long as it is not too dry. It does not tolerate coastal winds well. Its main attraction is its bark, but its moderate growth and slow growth are real assets for medium-sized gardens. However, it will stand out particularly well in winter! It can be highlighted isolated in the middle of a lawn, where one can enjoy its light shade. The Erman Birch also lends itself to superb winter compositions with other remarkable plants in winter, such as multicoloured bark Cornus or fragrant winter-flowering Hamamelis. It also allows provides contrasting colour combinations, for example when paired with black Ophiopogon, certain purple Hellebores, or the foliage of 'Black Lace' Elderberry in summer. Its autumn foliage will blend well with Nyssa sylvatica in acidic and moist soil, with deciduous Viburnums (Viburnum lantana, V. opulus, and their cultivars...) or Parrotia persica in drier, slightly chalky soil. It should be given a sunny location or partial shade to allow for easier growth.