The red berries and prickly leaves of the holly tree are symbolic of Christmas in the British Isles and the English-speaking world, though numerous cultures throughout the centuries have created their own symbolism for the holly tree. There are over 400 known species of the holly tree, all of which range in height. The majority of cultivated holly tree species originated in China, Japan, North America and Europe.
The holly tree is a member of the Ilex genus and comes in a wide range of shapes and sizes. Evergreen hollies retain their leaves throughout the year while deciduous hollies drop their leaves during the winter. Evergreen hollies include the American holly, the English holly, the Chinese holly, the Japanese holly, the inkberry holly, the long stalk holly, the myrtle leaf holly, the yaupon holly, the Nepal holly, the ciliospinosa holly, the large leaf holly, the perny holly, the kurogane holly and the dahoon holly. Deciduous hollies include the ambiguous winterberry holly, the possumhaw holly, the swamp holly, the finetooth holly and the winterberry holly.
The height of a full-grown holly tree varies depending on the species. In general, holly trees can grow between 6 and 18 m (20 and 60 feet) once fully mature, while holly shrubs can grow between 30 cm and 6 m (1 and 20 feet). Both male and female holly trees exist, but only the female version can bear fruit. Fruit appears on a female holly tree after pollination. Depending on the species, the fruit of a holly tree can either be orange, red, white, black or yellow.
Some of the insects known to harm the holly tree include leafminers, leaf feeders, mites, scales and spittlebugs. Leafminers, such as black flies, can damage the leaves of the holly tree and prevent them from growing properly. Leaf feeders, such as the black vine weevil and rough strawberry root weevil, feast upon the leaves of the holly tree. Mites and scales can alter the appearance of the holly tree's leaves, turning them a shade of yellow. Spittlebugs feed upon the sap of holly tree branches and lay eggs within dying branches.
Ancient Greeks used holly as a symbol of foresight while the Romans used holly as a symbol of good will and sent it out to friends during the Saturnalia celebration. Ancient Chinese cultures would decorate their homes with holly during New Year festivals. The English believed that if holly wasn't removed from the house after New Year's Eve, bad luck would follow. The Chinese, North American Indians and Europeans used holly concoctions to cure restlessness, fever, measles, kidney disease, childbirth pains, smallpox and coughs. The holly tree is also considered sacred among those who practice Witchcraft.