water-sprout

Rhizophora mangle

Rhizophora mangle, known as the red mangrove, is distributed in estuarine ecosystems throughout the tropics. Its viviparous seeds, which are dispersed by water, sprout while they are still on the parent plant, growing a tough green root that makes them unmistakable.

R. mangle grows on prop roots, which arch above the water level, giving stands of this tree the characteristic "mangrove" appearance. It is a valuable plant in Florida, Louisiana, and Texas costal ecosystems. In its native habitat it is threatened by invasive species such as the Brazilian Pepper Tree. The Red Mangrove itself is considered an invasive species in some locations, such as Hawaii, where it outcompetes native vegetation and forms dense, monospecific thickets. R. mangle thickets, however, are known to provide nesting and hunting habitat for a diverse array of organisms, including fish, birds, and crocodiles.

Habitat

Red Mangroves are found in subtropical and tropical areas in both hemispheres, extending to approximately 28°. They thrive on coastlines in brackish water and in swampy salt marshes. Because they are well adapted to salt water, they thrive where many other plants fail and create their own ecosystems, the mangals. Red mangroves are often found near white mangroves (Laguncularia racemosa), black mangroves (Avicennia germinans), and buttonwood (Conocarpus erectus). Though these plants are only distantly related, they serve a similar ecological purpose. Red Mangroves are usually the dominant species. Through stabilisation of their surroundings, mangroves create a community for other plants and animals (such as the mangrove crab) to survive. Though rooted in soil, mangrove roots are often submerged in water for several hours or on a permanent basis. The roots are usually sunk in a sand or clay base which allows for some protection from the waves.

Description

Red Mangroves are easily distinguishable through their unique prop root system and viviparous seeds. The prop roots of a red mangrove suspend it over the water, thereby giving it extra support and protection. They also help the tree to combat anaemia by allowing it a direct intake of oxygen through its root structure.

A mangrove can reach up to 80 feet in height in ideal conditions, however it is commonly found at a more modest 20 feet. Its bark is thick and a grey-brown color. Mangrove leaves are 1”-2” long and 3”-5” wide, with smooth margins and an ellipse shape. They are a darker shade of green on the tops then on the bottoms. The tree produces pale yellow flowers in the spring.

Reproduction

As a viviparous plant, the mangrove creates a fruit that is in reality a living tree. Through resembling an elongated seedpod, the fruit on the mangrove is capable of rooting at any time and producing a new tree. The trees are hermaphrodites, capable of self-pollinating or wind-pollinating. The tree undergoes no dormant stage as a seed, but rather progresses to a live plant before leaving its parent tree. A mangrove sapling may float in brackish water for over a year before rooting. It has been proposed that the life cycle of the red mangrove is in some unknown way linked to hurricane cycles, though this has never been proven.