Verbena Family (Verbenaceae)

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Verbena Family (Verbenaceae)

Tropical hardwoods in the verbena family

Ornamental species

North American species

Resources

The verbena or vervain family (Verbenaceae) is a diverse group of about 3,000 species of plants, most of which occur in the tropics.

Plants in this family can be herbs, shrubs, trees, or lianas (tropical vines). The leaves are usually simple, arranged alternately on the stem, which is often square-sided. The flowers are small, but often occur in attractive inflorescences.

Some species of trees in the verbena family are extremely valuable for the production of lumber.

Tropical hardwoods in the verbena family

Teak (Tectona grandis) is one of the worlds most prized species of tropical hardwood. Teak is a large tree of mature, tropical forests of South and Southeast Asia, and can grow as tall as 131 ft (40 m). Teak lumber can vary in color from light to brownish yellow, or a deep chocolate-brown. Lumber made from teak is heavy, strong, durable, resistant to splitting and cracking, and highly resistant to damages associated with immersion in water. Teak wood contains an aromatic, resinous oil that makes the wood feel slightly greasy to the touch, and helps to make it almost invulnerable to termites and highly resistant to wood-rotting fungi. Teak is valued for the manufacture of durable decking and trim on boats, and for making flooring, panelling, and fine furniture.

Teak is harvested from tropical forests wherever it occurs in Asia. Typically, teak trees are girdled and stripped of their lower bark, and then left standing for two years prior to felling. This allows the trees to dry somewhat before they are cut down, so the logs will be lighter and can be more easily dragged out of the forest. After the teak trees are felled they are sectioned into manageable-sized logs. These are then transported out of the forest using elephants or mechanical skidders, often to a river, on which the logs are floated to the coast for processing into lumber or veneer.

Unfortunately, teak occurring in natural forests is rarely harvested on a sustainable basis, and the resources of this extremely valuable tropical hardwood are being rapidly mined. Today and more so into the future, much of the teak available in commerce must be grown in plantations established for the production of this precious wood.

Other tropical species of tree in the Verbena family are also valuable as sources of hardwood lumber. These include species of Petitea, Premna, and Vitex celebica. Zither wood is a specialized material derived from Citharexylum spp. of Central and South America, and used to manufacture musical instruments.

The tropical trees Lippia citriodora and Vitex agnus-castus are useful as a source of natural oils, known as oil of verbena.

Ornamental species

Some species in the Verbena family are cultivated for their showy flowers. The most common garden verbenas in North American gardens are Verbena hortensis and V. hybrida, both frequently used as bedding plants. Two native species with showy flowers, the large-flowered verbena (Verbena canadensis) and small-flowered verbena (V. bipinnatifida), are commonly grown in gardens, and are often crossed with other verbenas to develop new varieties for horticulture. Purple mulberry (Callicarpa purpurea) is an attractive Asian shrub that is sometimes cultivated in North America.

KEY TERMS

Inflorescence A grouping or arrangement of florets or flowers into a composite structure.

Tropical hardwood A generic term for a wide variety of species of tropical, angiosperm trees. Tropical hardwoods have a heavy, dense wood that is valuable for the manufacturing of lumber, or composite materials such as plywood. Mahogany and teak are among the most prized of the tropical hardwoods.

Veneer A composite wood product, in which a thin outer covering of a valuable wood is glued onto an interior of less expensive wood.

Weed Any plant that is growing abundantly in a place where humans do not want it to be.

Several vines and shrubs in the genus Clerodendrum are sometimes grown as ornamentals in temperate areas, including the bleeding-heart (C. thomsoniae) and the pagoda flower (C. paniculatum). The shrub known as the lilac chaste tree (Vitex agnus-castus) is sometimes cultivated for its attractive, blue or white flowers. The beauty-berry (Callicarpa americana) is sometimes grown for its ornamental fruits.

Attractive species of Lantana are often cultivated as greenhouse and bedding plants. Unfortunately, some species of Lantana have escaped from gardens in the tropics, and in many places these have become serious weeds of pastures because livestock can be poisoned by eating this plant. Some horticultural species in the verbena family have also become naturalized as weeds in North America.

North American species

A number of species of wildflowers in the verbena family occur naturally in North America, or have been introduced from elsewhere and have spread to natural habitats.

One of the more familiar native species of verbenas in North America is the blue vervain or wild hyssop (Verbena hastata), a common plant of moist, temperate habitats. The French or Bermuda mulberry (Callicarpa americana) is a native shrub of moist thickets in southern parts of North America.

The European vervain or berbine (Verbena officinalis) is a common, introduced species in North America, and is sometimes an important weed.

Resources

BOOKS

Hartmann, H.T., A.M. Kofranek, V.E. Rubatzky, and W.J. Flocker. Plant Science. Growth, Development, and Utilization of Cultivated Plants. 4th ed. Englewood Cliffs, NJ: Prentice-Hall, 2006.

Bill Freedman

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Verbena Family (Verbenaceae)

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