holly

Ilex
Ilex paraguariensis
Scientific classification
Kingdom:	Plantae
Division:	Angiosperms
Class:	Eudicots
Order:	Aquifoliales
Family:	Aquifoliaceae DC. ex A.Rich.
Genus:	Ilex L.
Species
About 600, see text

European Holly (Ilex aquifolium) leaves and fruit

Ilex ( /ˈaɪlɛks/), or holly,^[1] is a genus of 400 to 600 species of flowering plants in the family Aquifoliaceae, and the only living genus in that family. The species are evergreen and deciduous trees, shrubs, and climbers from tropics to temperate zones worldwide.

Description

Ilex is a genus belonging to the family Aquifoliaceae, native of Afro-Eurasia, Australia and the Americas, established by Carl Linnaeus. It has over 300 species in the subtropical regions of both hemispheres. The genus includes species of trees, shrubs, and climbers, with evergreen or deciduous foliage and inconspicuous flowers. The genus was more extended in the tertiary and many species have adapted to laurel forest habitat. Ilex is adapted from sea level to more than 2,000 metres (6,600 ft) with high mountain species. Ilex are dioecious and have smooth, glabrous, or pubescent branchlets. The plants are generally slow-growing but over time can reach more than 10 m (33 ft). The genus name aquifolium is derived from the Latin (acer = "acute" & folium = "leaf"). Many are evergreen tree with some species growing to 25 m (82 ft) tall. Type species is the Mediterranean Ilex aquifolium described by Linnaeus.^[2]

Plants in this genus have simple, alternate glossy leaves, typically with a spiny toothed, or serrated leaf margin.

Ilex genus members also have small flowers. The flower is from greenish to white, with four petals. Male and female commonly flower on different plants, although there are exceptions. The pollination is done by bees and other insects.

The small fruits of Ilex, although often referred to as berries, are technically drupes^[3]. They range in color from red to brown to black, and rarely green or yellow. The "bones" contain up to ten seeds each. Some species produce fruits parthenogenetically, such as the cultivar 'Nellie R. Stevens'. The fruits ripen in winter and offer a pleasant color contrast with that of the plants' foliage. They are generally slightly toxic and can cause vomiting and diarrhea when ingested by humans. However, they are a very important food source for birds and other wildlife, and in winter the Ilex is an important source of food and shelter.

Ecology

North American Ilex mucronata formerly named Nemopanthus mucronata.

Hollies (here, Ilex aquifolium) are dioecious: (above) shoot with flowers from male plant; (top right) male flower enlarged from female plant; (lower right) female flower enlarged, showing stamen and reduced, sterile stamens with no pollen.

The phylogeography of this group provides examples of various speciation mechanisms at work. In this scenario ancestors of this group became isolated from the remaining Ilex when the Earth mass broke away from Gondwana and Laurasia about 82 million years ago, resulting in a physical separation of the groups and beginning a process of change to adapt to new conditions. This mechanism is called allopatric speciation. Over time survivor species of the holly genus adapted to different ecological niches. This led to reproductive isolation, an example of ecological speciation. In the Pliocene, around five million years ago, the formation of the new orogeny^{[clarification needed]} diversified the landscape and provided new opportunities for speciation within the genus.

The fossil record indicates that the Ilex lineage was already cosmopolitan long before the end of the Cretaceous. Based on the molecular clock the common ancestor of most of the extant species probably appeared during the Eocene, about 50 million years ago, suggesting that older representatives of the genus belong to now extinct branches.^[4] The laurel forest habitat, where most of the species of the genus Ilex are present then and now, covered great areas of the Earth, during the Paleogene, when the genus Ilex was more prosperous. This type of forest extended during the Neogene, more than 20 million years ago. Most of the last remaining temperate evergreen forests are believed to have disappeared about 10,000 years ago at the end of the Pleistocene. Many of the then existing species with strictest ecological requirements became extinct because they could not cross the barriers imposed by the geography, but others found refuge as a species relict in coastal enclaves, archipelagos, and coastal mountains sufficiently far from the extreme cold and aridity and protected by the oceanic influence.

The genus includes about 400 to 600 species, divided into three subgenera:

• Ilex subg. Byronia, with the type species Ilex polypyrena
• Ilex subg. Prinos, with 12 species
• Ilex subg. Ilex, with the rest of the over 400 species

The genus is distributed throughout the world's different climates. Most species make their home in the tropics and subtropics, with a wide distribution in temperate zones of Asia, Europe, Africa, North America and South America, but also in remote areas like Australia and the Pacific Islands. The greatest diversity of species is found in the Americas and in Southeast Asia.

Ilex mucronata was formerly the type species of Nemopanthus, is native to eastern North America.^[5] Nemopanthus was treated as a own monotypic genus with eight species ^[6] of the family Aquifoliaceae, now transferred to Ilex on molecular data;^[7] it is closely related to Ilex amelanchier.^[8] In Europe the genus is represented by a single species, the classically named Holly Ilex aquifolium. In continental Africa this former and (Ilex mitis). Ilex canariensis in the Macaronesia and Ilex aquifolium arose from a common ancestor in the area of laurisilva in the Mediterranean area. The early isolated Australia have (Ilex arnhemensis). In China grow 204 species, of which 149 species are endemic. Which stands out for its economic importance among the Spanish-speaking countries is Ilex paraguariensis or Yerba mate. Having evolved numerous species that are endemic to islands and small mountain ranges, and being highly useful plants, many hollies are now becoming rare. Often the tropical species are especially threatened by the habitat destruction and overexploitation. At least two species of Ilex have become extincts recently, and many others are barely surviving. ^[9] The fruits are toxic to humans, though their poisonous properties are overstated and fatalities are almost unknown. ^{[10] [11]} They are extremely important food for numerous species of birds, and also are eaten by other wild animals. In the autumn and early winter the fruits are hard and apparently unpalatable. After being frozen or frosted several times, the fruits soften, and become milder in taste. During winter storms, birds often take refuge in hollies, which provide shelter, protection from predators (by the spiny leaves), and food. The flowers are sometimes eaten by the larva of the Double-striped Pug moth (Gymnoscelis rufifasciata). Other Lepidoptera whose larvae feed on holly include Bucculatrix ilecella, which feeds exclusively on hollies, and The Engrailed (Ectropis crepuscularia).

Etymology

Originally the name of "ilex" was that of the European species (Ilex aquifolium), many representatives of the genus Ilex were also called by the common name “holly” because of the obvious resemblance. In Roman times, the Roman people in Latin language originally designated as Ilex the evergreen oak, named today scientifically (Quercus ilex). The leaves of the holly actually recall those of the oak.

The origin of the word "holly" is considered a reduced form of Old English hole(ġ)n,^[12]Middle English Holin, later Hollen.^{[13] [14]} The French word for holly, houx, derives from the Old Low Franconian *hulis (Middle Dutch huls).^[15] Both are related to Old High German hulis, huls,^[16] as do Low German/Low Franconian terms like Hülse or hulst. These Germanic words appear to be related to words for holly in Celtic languages, such as Welsh celyn, Breton kelen(n) and Irish cuileann. ^[17] The botanical name ilex was the original Latin name for the Holm Oak (Quercus ilex), which has similar foliage to common holly, and is occasionally confused with it. ^[18] Several romance languages use the Latin word acrifolium (turned into aquifolium in modern time), so Italian agrifoglio, Occitan grefuèlh, etc. ^[19]

Miscellaneous

A 'Highclere' holly variety

The berries of various species are slightly toxic to humans, although its poisonous properties have been exaggerated and poisoning deaths are almost unknown. Berries attract birds that eat them after the frosts have reduced toxicity.

Several holly species are used to make caffeine-rich herbal teas. The South American Yerba Mate (I. paraguariensis) is boiled for the popular revigorating drinks Mate, and Chimarrão, and steeped in water for the cold Tereré. Guayusa (I. guayusa) is used both as a stimulant and as an admixture to the entheogenic tea ayahuasca; its leaves have the highest known caffeine content of any plant. In North and Central America, Yaupon (I. vomitoria), was used by southeastern Native Americans as a ceremonial stimulant and emetic known as "the black drink".^[20] As the name suggests, the tea's purgative properties were one of its main uses, most often ritually. Gallberry (Appalachian Tea, I. glabra) is a milder substitute for Yaupon and does not have caffeine. In China, the young leaf buds of I. kudingcha are processed in a method similar to green tea to make a tisane called kǔdīng chá (苦丁茶, roughly "bitter spikeleaf tea").

Traditional Christmas card with generic "holly". Circa 1880s

Holly is commonly referenced at Christmas time. In many western cultures, holly is a traditional Christmas decoration, used especially in wreaths. Many of the hollies are widely used as ornamental plants in gardens and parks. Several hybrids and numerous cultivars have been developed for garden use, among them the very popular "Highclere hollies", Ilex × altaclerensis (I. aquifolium × I. perado) and the "blue hollies", Ilex × meserveae (I. aquifolium × I. rugosa).^[21] Hollies are often used for hedges; the spiny leaves make them difficult to penetrate, and they take well to pruning and shaping.^[22] In heraldry, holly is used to symbolise truth.

Between the thirteenth and eighteenth centuries, before the introduction of turnips, holly was cultivated for use as winter fodder for cattle and sheep.^[23] Less spiny varieties of holly were preferred, and in practice the leaves growing near the top of the tree have far fewer spines making them more suitable for fodder.

Holly was also once among the traditional woods for Great Highland bagpipes before tastes turned to imported dense tropical woods such as cocuswood, ebony, and African blackwood.^[24]

The Norwegian municipality of Stord has a yellow twig of Holly in its Coat-of-arms.

Selected species

Gallery

• 

  Ilex anomala

• 

  A contorted hedgehog holly Ilex aquifolium 'Ferox'

• 

  Ilex chinensis

• 

  Ilex pedunculosa

• 

  Ilex rotunda

• 

  Ilex verticillata

• 

  Ilex yunnanensis

• 

  Ilex × meserveae

• 

  Ilex pernyi from west China.

References

External links

• Media related to Ilex at Wikimedia Commons
• The Wiktionary entry for ilex
• Quotations related to Holly at Wikiquote