Unusual Trees

There are many types of unusual trees around the world that exhibit a variety of interesting characteristics. Among these are prehistoric relics, trees that exhibit bizarre growth patterns or formations, and trees with interesting strategies for obtaining the air, water, and nutrients necessary for growth.

Baobab, common name for a tropical African tree. The baobab tree grows only to the height of a large maple tree, but extensive lateral growth makes it one of the largest trees. The trunk of the baobab sometimes attains a diameter of 30 feet, and the branches, frequently as thick as the trunks of other large trees, form a hemispherical mass of foliage often 150 feet in diameter. The fruit, called monkey bread, is about the size of a citron; the pulp, which has a pleasing acid taste, is used in the preparation of cooling drinks. The bark of the tree yields a strong cordage fiber. The baobab, native to Africa, is now cultivated in many tropical countries throughout the world.

Banyan, common name for a large Indian tree, remarkable for numerous aerial roots that, growing down from the branches, take root in the soil and form prop roots or secondary trunks. In this manner the tree spreads over a large area. As the tree ages, the original trunk decays, and the tree breaks up into several sections, the props becoming separate trunks for the various sections. The banyan is a species of fig, with heart-shaped leaves about 6 inches long. The fruit is scarlet, about the size of a cherry, and grows in pairs from the axils of the leaves. The seeds seldom germinate in the ground, but, deposited by birds in the crowns of palm trees, germinate there and send down roots that embrace and eventually kill the palms. A famous banyan in the Botanical Gardens in Calcutta is more than a century old. The main trunk is more than 40 feet in circumference; it has 230 prop roots 6 to 10 feet around, and more than 3000 smaller trunks. Banyan trees can live to be well over 100 years old.

Like the ginkgo, the dawn redwood is old enough to be considered a living fossil. Its fossilized remains were studied and identified in the 1800s, and scientists believed that the tree had become extinct about 20 million years ago. In 1941, however, a Chinese botanist discovered living trees in an isolated valley in central China. Since then, the tree has been found in other places in China, and the fossil record indicates that millions of years ago it grew in Greenland and in North America as far south as California. Like other sequoias, the dawn redwood grows well from seeds, and seedlings have been planted throughout the Pacific Northwest and in Alaska. Specimen trees have also been successfully grown in many of the milder parts of the East Coast of the United States. Unlike other sequoias, the dawn redwood is deciduous and loses its leaves in the fall. The dawn redwood is considered to be ancestral to the coast redwood and giant sequoia. Young dawn redwoods such as this specimen are now cultivated throughout the world.

Great Basin bristlecone pine can live over 4000 years and is believed to be one of the oldest living trees on the planet. All members of the pine family have needlelike leaves, generally longer than those of other conifers, which appear in clusters of two to five, depending on the species. Pines are extremely adaptable to a range of climatic and soil conditions and are widespread in their distribution.

Although it is native to Africa, the sausage tree is cultivated as an ornamental in warm areas such as southern Florida and Hawaii. The sausage tree has large deep red flowers, which are replaced eventually by giant sausage-shaped fruits or woody capsules about 24 inches long, 4 inches wide, and weigh up to 12 pounds. The fruit takes a year to ripen and is inedible, but is often used in folk remedies for skin conditions.

Mission fig trees, (left) with roots that grow above ground, can reach 50 feet in height.

Bald cypress trees are needle-leaf trees that grow in swampy areas. These organs are extensions from the root system that project above the usual water level and absorb oxygen from the air for use by the roots. It grows very large, and it may live more than 12 centuries. Some specimens are 150 feet tall with a limb spread of 80 feet. In swamps the roots spread out for support. Some of the roots send knobby "knees" up above the water to get air. The tree is called "bald" because, though a conifer, it sheds its leaves in the fall.

Strangler fig trees are an example of a parasitic method of development that occurs in several plant families. A seed is deposited by a bird, monkey, or other animal in a depression or a crotch of a limb. The seed sprouts and begins to develop, and roots eventually find their way to the ground, sometimes traveling 25 m (82 ft) or more. There the roots take hold and begin to enlarge toward each other, enclosing the trunk of the host tree. Finally, the roots join side by side to restrict the growth of the original tree, which eventually rots away, leaving the parasite standing as an independent plant.

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