Ilex aquifolium

Ilex aquifolium
Scientific classification
Kingdom:	Plantae
(unranked):	Angiosperms
(unranked):	Eudicots
(unranked):	Asterids
Order:	Aquifoliales
Family:	Aquifoliaceae
Genus:	Ilex
Species:	I. aquifolium
Binomial name
Ilex aquifolium L.

Ilex aquifolium, holly, or european holly, is a species of holly native to western and southern Europe, northwest Africa and southwest Asia.

Overview

Holly, or European holly to distinguish it from related species, is also called Christmas holly or Mexican holly. It is a dioecious tree or shrub found, for example, in shady areas of forests of oak and in beech hedges. It has a great capacity to adapt to different conditions and is a pioneer species that repopulates the margins of forests or clearcuts. As a tree, it can exceed 10 m in height. It is usually found as a shrub or a small tree about 6 or 7 feet tall with a straight trunk and pyramidal crown, which branches from the base. It is slow growing and it does not usually fully mature due to grazing, cutting, or fire. It can live 500 years, but usually does not reach 100. The old trees are scarce. It originated in southern and south western Europe, from where it spread to the central and western Europe, the North Sea and Australia.

The toxicity of the fruit necessitates care when handling. Toxins include among others, alkaloids, caffeine and theobromine. The seeds are spread by blackbirds and other thrushes, pigeons, robins, warblers, etc. Toxins from the fruits are not harmful to birds. After the first frost of the season, the fruit becomes soft and falls to the ground serving as important food for winter birds. This evergreen tree with its thorny leaves is a popular place for smaller birds to roost in the winter.

It has great ecological value because it is a rugged pioneer species that preserves and enriches the soil facilitating colonization by others. It is of great value to birds and other fauna, including invertebrates that feed on their fruits and disperse their seeds. It is an ecological indicator of a well-preserved area, slightly degraded or recovering. Where a population of hollies thrives, it is indicative of an area with little human intrusion. They are usually found in isolated communities and remote areas. It prefers relatively moist areas, up to 600 m in height. It supports Mediterranean summer drought and frost. The plant is common in the garrigue and maquis. It appears in deciduous forest and oak forest. It has a gray trunk and can have several trunks or stems when grown as a shrub. It usually reaches 5 m in height, although in rare cases can reach 25 m if it has enough time to grow. It can be found in meso- and thermo floors, to 1,500 meters. It prefers moisture and resists cold. It requires a sunny position and is more abundant in average soils, tolerating the salty and slightly chalky, growing at the bottom of gorges and steep rocky slopes. Pure stands of hollies can grow into a labyrinth of vaults in which thrushes, and deer take refuge. The fact that it bears fruit in winter gives this plant a very important ecological value, being a good food source for many species, especially birds, at a time of scarce resources. These same fruits are considered purgative and emetic to humans.

Description

European holly foliage with berries

European holly flowers; male above, female below (leaves cut to show flowers more clearly)

It is an evergreen tree growing to 10–25 m tall and 40–80 cm, rarely 1 m or more, trunk diameter, with smooth grey bark. The leaves are 5–12 cm long and 2–6 cm broad, variable in shape; on young plants and low branches, with three to five sharp spines on each side, pointing alternately upward and downward; on higher branches of older trees with few or no spines except for the leaf tip, often entire. It is a tertiary laurel forest relict species, when the european climate was cooler and wetter. It grows in full sun in northern regions. Holly prefers partial shade and soil with good drainage and acid. Live in different types of soils and can withstand even relatively dry climates. Cold tolerant and likes humidity. In cold winters can freeze some branches.

Its woody stem, has gray bark. It has smooth bark throughout its life. At first the bark is a greenish color and from the second or third year is taking a definite dark gray. Its shiny leaves with spiny edge, are evergreen, dark green on the upper surface and lighter on the underside, elliptical, leathery and about 5 to 9 cm long. Its leaves are persistent, simple, petiolate s, alternate, oval shaped, with a hard edge prickly in the young and the lower limbs in adults, lacking spines of leafs of the upper branches. Last about five years and are very bright green and yellow-green on the underside, totally hairless, very stiff and leathery. Is a tree dioecious, ie, there are male plants and female plants. The females are those that produce berry-shaped fruits that mature turning red, if there are male plants near to fertilize. The germination of the seeds of holly is very irregular because it requires that the plants of both genders.

The flowers are dioecious, white, four-lobed, and pollinated by bees. The fruit is a red drupe 6–10 mm diameter, containing four pits; although mature in late autumn, they are very bitter due to the ilicin content, and so are rarely touched by birds until late winter after frost has made them softer and more palatable. Unable to determine the sex until the plants begin flowering, when having 4 to 12 years old. In male specimens, the flowers appear in axillary groups yellowish. In the female, isolated or in groups of three and are small and white or slightly pink, and consist of four petals and four sepals partially fused at the base.

Male and female flowers on different plant foot, small white, born from the axils of the leaves solitary or in clusters. Female specimens produce a fleshy fruit (drupe), a bright red or bright yellow, which matures very late, around October or November, and remains long in the tree, often throughout the winter. The red berry fruit is of the size of a pea. The fruits ripen in autumn and feed them rodents, herbivores and birds. For fruits that can germinate is necessary to have a male and one female for being a dioecious plant. Germination in this species does not occur until a year later, after growing very slowly. Contains within 4 or 5 "bones" (seed), which do not germinate until the second year, if ingested by a bird as the Blackbird. It flows well and poorly strain in the bud.

The fruits, red and fleshy, are typical of winter because this is precisely the ripening season. The fruits reach the crimson color typically in October and remain so during the cold months, which makes them a vital food source for forest animals. They are poisonous for human consumption.

Distribution

Holly is a very ancient species. Before the glaciers, the Holly occupied almost all of Europe, when Europe had a more humid and warmer climate. After the glacial period, the climate of Europa was made more unstable and seasonal, with hot dry summers and colder winters. Holly managed to adapt to this new climate and colder environments. The habitat of Holly today is in addition to humid Mediterranean areas, the Atlantic temperate zones of Europe and North Africa mountain. Native in the countries of the Mediterranean, it is now a protected species in some parts of Europe due to wild predation as Christmas decoration. Holly is found in western Asia and Europe in the undergrowth of oak forest and beech forest in particular, although at times it can form a dense thicket as the dominant species. As always requires moist, shady environments, it grows within the forest or in shady slopes, cliffs and mountain gorges. Amounts to more than 2000 meters and always fresh, loose soil, preferably silica. The laurel forest covered great areas of the Earth, during the Tertiary. This type of forest extended during the Cenozoic or Tertiary Era, more than 20 million years ago, over a wide area of the basin of the Mediterranean, Eurasia and north-west Africa where the climate the region were wetter. The laurisilvas forests was the vegetation type which originally covered much of Europe, and the Holly was a tipical representative species of laurel forest habitats, where many current species of the genus Ilex are present. With the drying of the Mediterranean Basin during the Pliocene, the laurel forests gradually retreated, replaced by more drought-tolerant sclerophyll plant communities. The modern european Ilex aquifolium resulted from this change. Most of the last remaining laurisilva forests around the Mediterranean are believed to have disappeared approximately 10,000 years ago at the end of the Pleistocene.

Miscellaneous

Holly berries are somewhat toxic to humans, though their poisonous properties are overstated and fatalities almost unknown.

Ilex aquifolium is used as a landscape tree in gardens in the West Coast of the United States. It is an invasive species on the West Coast of the United States and Hawaii.

Holly is rarely used medicinally due to its toxicity, but is diuretic, relieves fevers and has a laxative action.

It contains saponins, the xanthine theobromine and a yellow pigment, ilexanthin.