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The term "mangrove" may be used for a variety of tropical and subtropical plant species (in many cases not closely related to each other) that grow in highly saline coastal environments and as a consequence share many adaptations that allow them to survive and reproduce under these conditions (e.g., thick, waxy leaves to minimize water loss in their salty surroundings). Mangroves are trees or shrubs that grow with their roots partly or wholly submerged in sea water. The Red Mangrove (Rhizophora mangle) is particularly extreme in its ability to survive with its roots bathed in salt water. In Florida, Red Mangroves reach about 6 meters, but in the tropics they may grow to four times that height. The dark green leaves are shiny and broad. Reddish prop roots arch from the trunk into the water; old individuals may have aerial roots hanging from branches. Stalked yellow, waxy flowers are produced in groups of 4. The fruit is a leathery brown, conical berry about 2.5 cm long. The Red Mangrove is one of a number of mangrove species that are "viviparous", i.e., the seeds germinate while still attached to the parent. Red Mangrove seedlings (sometimes known as "sea pencils") up to 30 cm long hang from branches during much of the year. (Kaplan 1988)
Mangroves are builders. They help build up new land along the shore and are the anchors for rich and complex communities involving diverse animals, plants, fungi, and microorganisms (although plant species diversity in mangrove habitats is generally much lower than animal diversity). They serve as nurseries for many fish and invertebrates, including many that migrate along the shore or out into the ocean as adults. They filter the water and buffer the effects of hurricanes. Kaplan (1988) provides an excellent and accessible introduction to the ecology of mangroves and mangrove swamps.