Aquifoliaceae

Ilex /ˈaɪlɛks/, or holly, is a genus of about 480 species of flowering plants in the family Aquifoliaceae, and the only living genus in that family. The species are evergreen or deciduous trees, shrubs, and climbers from tropics to temperate zones worldwide. The genus Ilex includes about 480 species, divided into three subgenera: The genus is widespread throughout the temperate and subtropical regions of the world. It includes species of trees, shrubs, and climbers, with evergreen or deciduous foliage and inconspicuous flowers. Its range was more extended in the Tertiary period and many species are adapted to laurel forest habitats. It occurs from sea level to more than 2,000 metres (6,600 ft) with high mountain species. It is a genus of small, evergreen trees with smooth, glabrous, or pubescent branchlets. The plants are generally slow-growing with some species growing to 25 m (82 ft) tall. The type species is the European holly Ilex aquifolium described by Linnaeus. Plants in this genus have simple, alternate glossy leaves, frequently with a spiny leaf margin. The inconspicuous flower is greenish white, with four petals. They are generally dioecious, with male and female flowers on different plants. The small fruits of Ilex, although often referred to as berries, are technically drupes. 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 thus provide winter colour contrast between the bright red of the fruits and the glossy green evergreen leaves. Hence the cut branches, especially of I. aquifolium, are widely used in Christmas decoration. The fruits are generally slightly toxic to humans, and can cause vomiting and diarrhea when ingested. However, they are an important food source for birds and other animals, which help disperse the seeds. Unfortunately this can have negative impacts as well. Along the west coast of North America, from California to British Columbia, English holly (Ilex aquifolium), which is grown commercially, is quickly spreading into native forest habitat, where it thrives in shade and crowds out native species. It has been placed on the Washington State Noxious Weed Control Board's monitor list, and is a Class C invasive plant in Portland. Ilex in Latin means the holm-oak or evergreen oak (Quercus ilex). Despite the Linnaean classification of Ilex as holly, as late as the 19th century in Britain, the term Ilex was still being applied to the oak as well as the holly – possibly due to the superficial similarity of the leaves. The name 'holly' in common speech refers to Ilex aquifolium, specifically stems with berries used in Christmas decoration. By extension, 'holly' is also applied to the whole genus. The origin of the word 'holly' is considered a reduced form of Old English hole(ġ)n, Middle English Holin, later Hollen.The French word for holly, houx, derives from the Old Low Franconian *hulis (Middle Dutch huls). Both are related to Old High German hulis, huls, as are 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. Several Romance languages use the Latin word acrifolium, literally 'sharp leaf' (turned into aquifolium in modern time), so Italian agrifoglio, Occitan grefuèlh, etc. 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 into 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, mountain formation diversified the landscape and provided new opportunities for speciation within the genus.