Ilex crenata 'JENNY' Japanese holly

Ilex

The genus Ilex, known as holly, comprises more than four hundred species of evergreen and deciduous shrubs and trees distributed across much of the world, with centres of diversity in the subtropics and the mountainous regions of East Asia and the Americas. Botanically, the genus is characterised by leathery leaves, often with pronounced venation, inconspicuous flowers and striking fruits – drupes that are typically red, less commonly black or yellow. Most hollies are dioecious, meaning that male and female flowers occur on separate plants and fruit production requires the presence of both sexes. The genus was described by Carl Linnaeus (1707–1778), though its taxonomy continues to evolve due to high morphological variability, frequent hybridisation and the wide ecological range of individual species. Fossil and molecular evidence suggests that the main lineages of Ilex originated in the Eocene, indicating long-term stability and an ability to adapt to changing climatic conditions. 

Hollies have accompanied humans for millennia not only as useful and ornamental plants but also as powerful cultural symbols. In Europe, Ilex aquifolium is traditionally associated with the winter solstice, Christmas and the idea of protecting the home from evil forces, while in North America Ilex opaca was valued for its hard timber and medicinal properties. In East Asia, particularly in Japan, hollies found their place in garden art as plants expressing permanence, order and the ability to withstand adversity – values deeply rooted in local aesthetics. In modern landscape design, the genus Ilex has become a symbol of structure and endurance, whether in the form of formal hedges, shaped specimens or calm evergreen backdrops that persist even in winter.

Ilex crenata, Japanese holly, originates from Japan, Korea and eastern China, where it grows in mountain forests on acidic soils. It was first described by Carl Peter Thunberg (1743–1828), a Swedish botanist working in Nagasaki, who was one of the few Europeans of the 18th century to gain direct access to Japanese flora during the country’s strict isolation. It differs from other species of the genus by its small, glossy, spineless leaves, compact growth and ability to tolerate hard pruning, so many people mistake it at first glance for boxwood or even certain Lonicera species. This resemblance predestined it to become an ideal replacement for true boxwood, which has been steadily disappearing across Europe under the pressure of the massive invasion of the box tree moth and fungal diseases, especially box blight, which has devastated plantings on the British Isles. Japanese hollies are spineless, offer a wide range of shapes and sizes, require only minimal care and, thanks to their natural variability, frequently produce new cultivars, each slightly different from the last. In this way, Ilex crenata has evolved from a botanical curiosity into a key plant of contemporary garden design, capable of taking over the role of a historically rooted element of formal gardens, cemeteries and urban parterres without the need for chemical protection.