mangrove

mangrove, large tropical evergreen tree, genus Rhizophora, that grows on muddy tidal flats and along protected ocean shorelines. Mangroves are most abundant in tropical Asia, Africa, and the islands of the SW Pacific. The American, or red, mangrove (Rhizophora mangle) is found along the muddy shores and in the everglades of the Florida peninsula and on other tropical American coast lines.

Mangroves produce from their trunks aerial roots that become embedded in the mud and form a tangled network; this serves both as a prop for the tree and as a means of aerating the root system. Such roots also form a base for the deposit of silt and other material carried by the tides, and thus land is built up which is gradually invaded by other vegetation. The mangrove forests also can protect inland coastal areas by absorbing the effects of storm and some tsunami waves, but many mangroves have been harvested destructively on a large scale. The bark is a rich source of tannins, and the wood is used for wharf pilings and other purposes.

Some mangrove species lack prop roots but have special pores on their branching root system for obtaining air. The mangrove fruit is a conical reddish brown berry. Its single seed germinates inside the fruit while it is still on the tree, forming a large, pointed primary root that quickly anchors the seedling in the mud when the fruit is dropped.

The name mangrove is also applied to other unrelated constituents of mangrove vegetation, such as Avicennia nitida, a bush of the vervain family, called black mangrove. True mangroves are classified in the division Magnoliophyta, class Magnoliopsida, order Rhizophorales, family Rhizophoraceae.

Bibliography

See P. B. Tomlinson, The Botany of Mangroves (1986).

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mangrove

Any of certain shrubs and trees of the families Rhizophoraceae, Verbenaceae, Sonneratiaceae, and Arecaceae (palm) that grow in dense thickets or forests along tidal estuaries, in salt marshes, and on muddy coasts. The term also applies to the thickets and forests of such plants. Mangroves characteristically have prop roots (exposed, supporting roots). In addition, in many species respiratory, or knee, roots project above the mud and have small openings through which air enters, passing through the soft, spongy tissue to the roots beneath the mud. Mangrove fruits put out an embryonic root before they fall from the tree; the root may fix itself in the mud before the fruit separates from the parent. Likewise, branches and trunks put out adventitious roots which, once they are secure in the mud, send up new shoots. The common mangrove (Rhizophora mangle) grows to about 30 ft (9 m) tall and bears short, thick, leathery leaves on short stems, and pale-yellow flowers. Its fruit is sweet and wholesome.