Holly Family (Aquifoliaceae)

views updated

Holly Family (Aquifoliaceae)

Members of the holly family (Aquifoliaceae) are shrubs and trees with small white or pale green unisexual flowers. The family consists of four genera with 419 species, of which 400 are members of the holly genus, Ilex. The family Aquifoliaceae is a member of the class Magnoliopsida (dicotyledons), division Magnoliophyta (the angiosperms, or flowering plants).

Characteristics of holly

Most hollies are dioecious, meaning a plant is either a male (staminate) or a female (pistillate). Holly

flowers have radial symmetry, and are four-merous, that is, the flowers are round and floral parts occur in fours. Holly flowers have four sepals, four petals, four stamens (male flowers), and an ovary made up of four fused carpels, called a pistil (female flowers).

The fruit is a drupe, which is similar to a berry, but with hard seeds instead of soft seeds, and may be red, orange, yellow, or black in color. The drupes of Ilex spp. are eaten by wildlife, especially birds. Bird droppings effectively disperse holly seeds, which pass through the bird’s digestive tract undamaged. Indeed, hollies are often seen sprouting along fence rows and under other places where birds roost. Holly leaves may also be a source of food for wildlife, as they are sometimes grazed by deer.

Hollies may be evergreen or deciduous, depending on whether a species retains its foliage throughout the year or loses its leaves in the fall. One of the more spectacular of the deciduous hollies is winterberry (Ilex verticillata). Occurring in the eastern United States and southeastern Canada, winterberry is known and loved for its crimson colored berries, which provide a stark contrast to the winter landscape. Holly leaves are alternate, occurring one at a time on alternating sides of a branch. Leaves are simple (as opposed to compound), and leaf margins may be entire, wavy, or spiny.

Distribution and ecology of hollies

The holly family occurs in most temperate and tropical regions, except Australia and Africa. About 12 species of Ilex occur in North America. Sarvis holly (Ilex amelanchier), gallberry (Ilex glabra), large gallberry (Ilex coriacea), myrtle-leaf holly (Ilex myrtifolia), and winterberry inhabit swamps, bogs, and floodplains. Possum haw (Ilex decidua) occurs in floodplains and second-growth forests. Some hollies inhabit coastal areas, such as sand holly (Ilex ambigua) and dahoon holly (Ilex cassine). The American holly (Ilex opaca) is found in moist forests. In Florida, the scrub holly, a variety of American holly, inhabits sandy, oak scrub. Yaupon holly (Ilex vomitoria) occurs in coastal areas, scrub, and second-growth forests. The mountain holly, (Nemopanthus mucronata), occurs in the eastern region of North America.

Although most hollies are small trees or shrubs, some have reached a substantial size. For example, the largest dahoon holly, normally about 33 feet (10 m) tall, can reach a height of 79 feet (24 m). Yaupon holly, typically a small or shrubby tree can measure 49 feet (15 m) tall.

Ilex guianensis of Central America stands out from the other relatively shorter hollies. This species can reach a height of 141 feet (43 m). Like American hollies, the Asian hollies also occur in a variety of sizes and habitats. The tarago (Ilex latifolia) of Japan is a handsome tree, with large shiny leaves and red berries. This species may grow to 66 feet (20 m). The smaller Ilex integra of Japan is cultivated in tranquil temple gardens.

Uses by humans

Several species of Ilex are planted by homeowners for their attractive foliage and berries. Among the best known of the horticultural varieties are the American holly, yaupon holly, and winterberry. Because of their colorful berries which ripen by fall and winter, many hollies are used for indoor decorating, especially during the Christmas season. Holly boughs and wreaths are popular for this purpose. English holly (Ilex aquifolium) is commonly used for its attractive berries, but creative decorators will also collect leaves and berries from the native, North American hollies.

Long before the horticulture industry discovered the hardiness and attractiveness of hollies, Native Americans used the yaupon holly for medicinal and religious purposes. A dark tea was brewed from the leaves of yaupon holly, which, when consumed, induced sweating, excitation, bowel movement, and vomiting. Only men were allowed to consume this purgative tea. The compound in the holly leaves responsible for the reaction from the tea is the stimulant caffeine, also found in coffee. Of the 400 species of Ilex worldwide, only about 60 species are known to contain caffeine.

In South America, Paraguay tea or yerba mate, is brewed from the leaves of Ilex paraguariensis. This brew, like yaupon tea, is a stimulating drink containing caffeine. Although Paraguay tea can induce sweating and urination, it is widely used on a regular basis

KEY TERMS

Carpel —Female reproductive organ of flowers which is composed of the stigma, style, and ovary.

Deciduous —In plants, refers to leaves or other tissues which are shed at the end of the growing season.

Dioecious —Plants in which male and female flowers occur on separate plants.

Pistillate flower —A female flower, containing the pistil, the female sex organ which becomes the fruit after fertilization.

Radial symmetry —An arrangement of the floral parts characterized by their radiation from the center of the flower, like spokes on a bicycle wheel.

Stamen— Male reproductive organ of a flower that produces pollen.

Staminate flower —A male flower.

by many South Americans, just as North Americans drink coffee.

The bark of winterberry was used by native American Indians to brew a refreshing tonic, but direct consumption of the berries may induce vomiting. Winterberry bark has also been made into an astringent for the skin, and also as an antiseptic.

In addition to their usage as ornamentals and teas, hollies are also used as a source of wood. Because hollies are primarily of small stature, holly wood is used mainly for decorative inlays in furniture and in wood sculptures.