An Unknown And Exotic Privet

Ligustrum, commonly known as privet, is no exception. Perhaps surprisingly, it belongs to a family where you might not expect to find it – the olive family. This is a remarkably diverse group, including not only exotic olives and true jasmine, but also lilacs and ashes. This time, I would like to introduce two unusual and still rarely grown privet species, which will take us on a journey halfway around the globe – to Japan and China.

Japanese privet (Ligustrum japonicum) is an evergreen shrub or small tree native to central and southern Japan and Korea. It is a valued ornamental plant: smaller and dwarf cultivars are often trained as bonsai, while the wild botanical form is allowed to grow freely into extensive thickets and woodland margins, where it serves as a green barrier and provides shelter for birds and wildlife.

One of the most beautiful cultivars currently in cultivation is Texanum. It is easily recognised by its distinctive leaves, which are noticeably thicker and leathery, fresh green, highly glossy and always gently undulating. The underside of the leaves is very pale, and because the foliage is held upright, the contrast between upper and lower surfaces is particularly striking. ‘Texanum’ forms well structured, rather spreading shrubs with an attractive tiered habit – something quite unusual for privets, which typically grow in a more upright manner. No one knows for certain where this cultivar originated, but it is believed to have come from Texas, where Japanese privets were introduced in the second half of the 19th century and found excellent growing conditions – hence the name.

Another noteworthy cultivar of the Japanese species is the dwarf Korea Dwarf. It grows slowly and very densely and, in addition to its reliably evergreen foliage, stands out for its abundant flowering. All privets flower, usually from early to late summer, but because this cultivar is compact, the flowers are concentrated over a smaller area, creating an exceptionally rich display. The flowers are also pleasantly fragrant.

From Japan we now move to China, the home of glossy privet. This species is also reliably evergreen, although somewhat paradoxically its leaves are often less glossy than the name suggests. They are leathery and obovate, and young leaves may be flushed with burgundy, as seen in the modern cultivar Green Screen. As the name implies, it is ideal for hedges and garden screens, as it eventually forms almost impenetrable thickets. It flowers much later, towards the end of summer, and is grown not only as a shrub but also as an effective small tree, which in full bloom is literally covered in flowers.

In addition to green leaved forms, there is a particularly striking variegated cultivar, Excelsum Superbum. On my travels in southern Europe, I encounter it far more often as a tree than as a shrub, planted in urban avenues. A gardener friend of mine from Maryland in the USA has confirmed that it is also popular there as an evergreen street tree, thanks to its minimal maintenance requirements and excellent tolerance of summer heat and seasonal drought.

In its native range, Chinese privet has one fascinating additional role. It serves as the host plant for the insect Ericerus pela, which produces thick waxy coatings on the branches. These are scraped off in autumn, processed, and used to produce so called white wax, historically employed in candle making and traditional medicine. This practice is more than a thousand years old, and until the early 20th century, when it was replaced by artificially produced paraffin, white wax was among the most commonly used waxes. As a result, the collection and processing of white wax was considered an important craft, comparable to any other essential trade of its time.

The fruits of all privet species contain glycosides that are mildly toxic to humans and domestic animals. In the case of people, the advantage is that this can be explained; with pets, it helps that the fruits are usually borne higher up in the shrub, are not easily accessible and are generally unpalatable. In addition, entire fruiting panicles can easily be removed from the lower parts of the plant after flowering.

Both Asian privet species can be regarded as modern shrubs. They combine low demands on soil and irrigation with excellent adaptation to heat and drought. After planting, they require watering only briefly and later rely largely on natural rainfall. Only during dry winters should they receive some additional moisture. They tolerate acidic, neutral and alkaline soils and can grow in nutrient poor conditions, but they must never be planted in heavy, waterlogged ground. Frost hardiness has been tested down to −20 °C without damage, and newer cultivars and selections, such as ‘Green Screen’, have already withstood −23 °C. Further trials are ongoing.