Holly: a highly symbolic relict

The small, round fruit is deep red in colour and stands out among the dark green, glossy, jagged leaves. This is holly, an ancient species that has become a symbol of Christmas, but which the Celts worshipped centuries ago.

Holly is part of the collective imagination of a large proportion of the population, but more people recognise it from Christmas decorations than have ever seen it in nature. This is not surprising, as holly (Ilex aquifolium) is considered a relict species: a survivor of the subtropical forests (Laurissilva) that covered mainland Portugal before the Ice Age.

Although it managed to survive the intense climatic fluctuations of the Ice Age and continues to grow naturally in humid mountain areas, its presence today is much smaller than in those distant times.

In the 20th century, the excessive cutting of branches for Christmas decorations brought new pressures. To prevent it from disappearing in the wild, the uprooting and partial or total cutting of the trees, as well as transporting and selling them have been prohibited by Portuguese law since 1989. More recently, the Natura 2000 Network succeeded in establishing Ilex aquifolium forests as a natural habitat of community interest: habitat 9380. Even so, the International Union for the Conservation of Nature classifies holly as “Low Concern” on its Red List of Threatened Species.

How to recognise holly

A shrub or small tree, holly can grow to almost 20 metres in height, but it rarely exceeds four to six. A large specimen, measuring about 19 metres in height, can be seen in the Buçaco National Forest, near Porta de Sula. 7
The holly has both female and male plants (monoecious species). Its flowers are small, arranged in pinkish-white clusters, and appear between April and June. They are present both in the male plants, the pollen producers, and in the female plants that start to fruit after flowering.

The fruits emerge in summer and in autumn they start to change from green to red, a colour that lasts throughout winter. These fruits are rounded, fleshy drupes, about one centimetre in diameter, which hold the seed inside. They are toxic to humans, but are an important food source for various animals. Birds eat them without digesting them and return them to nature, which helps propagate the species.

The leaves are wavy and oval in shape, with a toothed, spiny edge which acts as a defence against plant-eating species (herbivores). They remain green all year round: they are darker and waxed on the upper side, and dull yellowish green underneath. In older trees, the edges of the leaves may soften and disappear because they are shielded from herbivores.

Did you know that holly…

• was venerated by the Celts: the earliest records of its use date back to the 3rd century BC It is thought that the species was a symbol of immortality and protection for them, as it remained evergreen and managed to bear fruit during cold, snowy winters. Later, the Romans offered it up to the god Saturn during the Saturnalia festivities–the winter solstice feast, since incorporated into the Christian celebration of Christmas. Interestingly, the name Ilex was given by the Romans to the holm oak (Quercus ilex) and was then applied to the holly by Linnaeus, due to the similarity between their leaves (albeit holm oak leaves are considerably smaller).
• is also sometimes confused with butcher’s-broom (Ruscus aculeatus). Although not related, there are some resemblances: the dark green leaves of the holly are a similar colour to the stems of the butcher’s-broom, which play the role of leaves (cladodes), and have a comparable shape and outline; another similarity is the small, rounded fruits, which appear in summer and turn red in winter. The most obvious difference is in the leaves: in the holly, these are indented and have a spiny edge, which is not the case for the butcher’s-broom. The size may also be different, because the butcher’s-broom is a shrub that usually only grows to a height of one and a half metres.
• has a related species, which is only found on Madeira and the Spanish Canary Islands, the Ilex canariensis. There is also an endemic subspecies in the Azores that is exclusive to the archipelago: Ilex perado subsp. azorica. Although it differs somewhat from Ilex aquifolium, it is of the same genus and family. They are all species that grow in the Laurisilva forest (found in both Portuguese archipelagos) and have small, round, red fruit.