Avicennia germinans
Encyclopedia
Avicennia germinans, commonly known as the black mangrove, is a species of flowering plant
in the acanthus family, Acanthaceae
.
A. germinans grows in tropical
and subtropical
regions of the Americas
, on both Atlantic
and Pacific
coast
s, and on the Atlantic coast of tropical Africa
, where it thrives on the sand
y and muddy shore
s that seawater
reaches. It can grow to heights of 15 m (49.2 ft) in the tropics, but becomes small and shrub
-like at the northern limits of its range. Black mangrove is common throughout coastal areas of Texas
and Florida
, and ranges as far north as southern Louisiana
and coastal Georgia
in the United States
.
Like many other mangrove
species, it reproduces by vivipary
. Seed
s are encased in a fruit
, which reveals the germinated
seedling when it falls into the water.
Unlike other mangrove species, it does not grow on prop roots, but possesses pneumatophores that allow its roots to breathe even when submerged. It is a hardy species and expels absorbed salt mainly from its leathery leaves.
The name black mangrove refers to the color of the trunk and heartwood. The leaves often appear whitish from the salt
excreted
at night and on cloudy days. It is often found in its native range with the red mangrove (Rhizophora mangle
) and the white mangrove (Laguncularia racemosa
). White mangroves grow inland from black mangroves which themselves grow inland from red mangroves. The three species work together to stabilize the shoreline, provide buffers from storm surge
s, trap debris and detritus
brought in by tide
s, and provide feeding, breeding, and nursery grounds for a great variety of fish
, shellfish
, bird
s, and other wildlife.
in coastal lagoon
s and brackish water
estuaries
. It is less tolerant of highly saline conditions that certain other species that occur in mangrove ecosystems. It can reach 10 – in height, although it is a small shrub
in the northern (colder) extent of its range. The seed
s germinate
in midsummer, but may be seen all year on the trees. The seeds can remain viable for over a year, once released.
, and fuel
. In spite of the fact the tree grows in a marine environment, the dry wood is subject to attack by marine borers and termite
s. Like many species, it contains tannin
in the bark and has been used to tan
leather
products.
Flowering plant
The flowering plants , also known as Angiospermae or Magnoliophyta, are the most diverse group of land plants. Angiosperms are seed-producing plants like the gymnosperms and can be distinguished from the gymnosperms by a series of synapomorphies...
in the acanthus family, Acanthaceae
Acanthaceae
The family Acanthaceae is a taxon of dicotyledonous flowering plants containing almost 250 genera and about 2500 species....
.
A. germinans grows in tropical
Tropics
The tropics is a region of the Earth surrounding the Equator. It is limited in latitude by the Tropic of Cancer in the northern hemisphere at approximately N and the Tropic of Capricorn in the southern hemisphere at S; these latitudes correspond to the axial tilt of the Earth...
and subtropical
Subtropics
The subtropics are the geographical and climatical zone of the Earth immediately north and south of the tropical zone, which is bounded by the Tropic of Cancer and the Tropic of Capricorn, at latitudes 23.5°N and 23.5°S...
regions of the Americas
Americas
The Americas, or America , are lands in the Western hemisphere, also known as the New World. In English, the plural form the Americas is often used to refer to the landmasses of North America and South America with their associated islands and regions, while the singular form America is primarily...
, on both Atlantic
Atlantic Ocean
The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...
and Pacific
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...
coast
Coast
A coastline or seashore is the area where land meets the sea or ocean. A precise line that can be called a coastline cannot be determined due to the dynamic nature of tides. The term "coastal zone" can be used instead, which is a spatial zone where interaction of the sea and land processes occurs...
s, and on the Atlantic coast of tropical Africa
Tropical Africa
Although tropical Africa is most familiar in the West as depicted by its rain forests, this region of Africa is far more diverse. While the tropics are thought of as regions with warm to hot moist climates caused by latitude and the tropical rain belt, the geology of areas, particularly mountain...
, where it thrives on the sand
Sand
Sand is a naturally occurring granular material composed of finely divided rock and mineral particles.The composition of sand is highly variable, depending on the local rock sources and conditions, but the most common constituent of sand in inland continental settings and non-tropical coastal...
y and muddy shore
Shore
A shore or shoreline is the fringe of land at the edge of a large body of water, such as an ocean, sea, or lake. In Physical Oceanography a shore is the wider fringe that is geologically modified by the action of the body of water past and present, while the beach is at the edge of the shore,...
s that seawater
Seawater
Seawater is water from a sea or ocean. On average, seawater in the world's oceans has a salinity of about 3.5% . This means that every kilogram of seawater has approximately of dissolved salts . The average density of seawater at the ocean surface is 1.025 g/ml...
reaches. It can grow to heights of 15 m (49.2 ft) in the tropics, but becomes small and shrub
Shrub
A shrub or bush is distinguished from a tree by its multiple stems and shorter height, usually under 5–6 m tall. A large number of plants may become either shrubs or trees, depending on the growing conditions they experience...
-like at the northern limits of its range. Black mangrove is common throughout coastal areas of Texas
Texas
Texas is the second largest U.S. state by both area and population, and the largest state by area in the contiguous United States.The name, based on the Caddo word "Tejas" meaning "friends" or "allies", was applied by the Spanish to the Caddo themselves and to the region of their settlement in...
and Florida
Florida
Florida is a state in the southeastern United States, located on the nation's Atlantic and Gulf coasts. It is bordered to the west by the Gulf of Mexico, to the north by Alabama and Georgia and to the east by the Atlantic Ocean. With a population of 18,801,310 as measured by the 2010 census, it...
, and ranges as far north as southern Louisiana
Louisiana
Louisiana is a state located in the southern region of the United States of America. Its capital is Baton Rouge and largest city is New Orleans. Louisiana is the only state in the U.S. with political subdivisions termed parishes, which are local governments equivalent to counties...
and coastal Georgia
Georgia (U.S. state)
Georgia is a state located in the southeastern United States. It was established in 1732, the last of the original Thirteen Colonies. The state is named after King George II of Great Britain. Georgia was the fourth state to ratify the United States Constitution, on January 2, 1788...
in the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
.
Like many other mangrove
Mangrove
Mangroves are various kinds of trees up to medium height and shrubs that grow in saline coastal sediment habitats in the tropics and subtropics – mainly between latitudes N and S...
species, it reproduces by vivipary
Vivipary
Vivipary has two different meanings. In animals, it means development of the embryo inside the body of the mother, eventually leading to live birth, as opposed to laying eggs...
. Seed
Seed
A seed is a small embryonic plant enclosed in a covering called the seed coat, usually with some stored food. It is the product of the ripened ovule of gymnosperm and angiosperm plants which occurs after fertilization and some growth within the mother plant...
s are encased in a fruit
Fruit
In broad terms, a fruit is a structure of a plant that contains its seeds.The term has different meanings dependent on context. In non-technical usage, such as food preparation, fruit normally means the fleshy seed-associated structures of certain plants that are sweet and edible in the raw state,...
, which reveals the germinated
Germination
Germination is the process in which a plant or fungus emerges from a seed or spore, respectively, and begins growth. The most common example of germination is the sprouting of a seedling from a seed of an angiosperm or gymnosperm. However the growth of a sporeling from a spore, for example the...
seedling when it falls into the water.
Unlike other mangrove species, it does not grow on prop roots, but possesses pneumatophores that allow its roots to breathe even when submerged. It is a hardy species and expels absorbed salt mainly from its leathery leaves.
The name black mangrove refers to the color of the trunk and heartwood. The leaves often appear whitish from the salt
Salt
In chemistry, salts are ionic compounds that result from the neutralization reaction of an acid and a base. They are composed of cations and anions so that the product is electrically neutral...
excreted
Halophyte
A halophyte is a plant that grows where it is affected by salinity in the root area or by salt spray, such as in saline semi-deserts, mangrove swamps, marshes and sloughs, and seashores. An example of a halophyte is the salt marsh grass Spartina alterniflora . Relatively few plant species are...
at night and on cloudy days. It is often found in its native range with the red mangrove (Rhizophora mangle
Rhizophora mangle
Rhizophora mangle, known as the red mangrove, is distributed in estuarine ecosystems throughout the tropics. Its viviparous "seeds," in actuality called propagules, become fully mature plants before dropping off the parent tree...
) and the white mangrove (Laguncularia racemosa
Laguncularia racemosa
Laguncularia racemosa is a species of flowering plant in the leadwood tree family, Combretaceae...
). White mangroves grow inland from black mangroves which themselves grow inland from red mangroves. The three species work together to stabilize the shoreline, provide buffers from storm surge
Storm surge
A storm surge is an offshore rise of water associated with a low pressure weather system, typically tropical cyclones and strong extratropical cyclones. Storm surges are caused primarily by high winds pushing on the ocean's surface. The wind causes the water to pile up higher than the ordinary sea...
s, trap debris and detritus
Detritus
Detritus is a biological term used to describe dead or waste organic material.Detritus may also refer to:* Detritus , a geological term used to describe the particles of rock produced by weathering...
brought in by tide
Tide
Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the moon and the sun and the rotation of the Earth....
s, and provide feeding, breeding, and nursery grounds for a great variety of fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...
, shellfish
Shellfish
Shellfish is a culinary and fisheries term for exoskeleton-bearing aquatic invertebrates used as food, including various species of molluscs, crustaceans, and echinoderms. Although most kinds of shellfish are harvested from saltwater environments, some kinds are found only in freshwater...
, bird
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...
s, and other wildlife.
Habitat
The black mangrove grows just above the high tideTide
Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the moon and the sun and the rotation of the Earth....
in coastal lagoon
Lagoon
A lagoon is a body of shallow sea water or brackish water separated from the sea by some form of barrier. The EU's habitat directive defines lagoons as "expanses of shallow coastal salt water, of varying salinity or water volume, wholly or partially separated from the sea by sand banks or shingle,...
s and brackish water
Brackish water
Brackish water is water that has more salinity than fresh water, but not as much as seawater. It may result from mixing of seawater with fresh water, as in estuaries, or it may occur in brackish fossil aquifers. The word comes from the Middle Dutch root "brak," meaning "salty"...
estuaries
Estuary
An estuary is a partly enclosed coastal body of water with one or more rivers or streams flowing into it, and with a free connection to the open sea....
. It is less tolerant of highly saline conditions that certain other species that occur in mangrove ecosystems. It can reach 10 – in height, although it is a small shrub
Shrub
A shrub or bush is distinguished from a tree by its multiple stems and shorter height, usually under 5–6 m tall. A large number of plants may become either shrubs or trees, depending on the growing conditions they experience...
in the northern (colder) extent of its range. The seed
Seed
A seed is a small embryonic plant enclosed in a covering called the seed coat, usually with some stored food. It is the product of the ripened ovule of gymnosperm and angiosperm plants which occurs after fertilization and some growth within the mother plant...
s germinate
Germination
Germination is the process in which a plant or fungus emerges from a seed or spore, respectively, and begins growth. The most common example of germination is the sprouting of a seedling from a seed of an angiosperm or gymnosperm. However the growth of a sporeling from a spore, for example the...
in midsummer, but may be seen all year on the trees. The seeds can remain viable for over a year, once released.
Wood
The heartwood is dark-brown to black, while the sapwood is yellow-brown. It has the unusual property of having less dense heartwood than sapwood. The sapwood sinks in water while the heartwood floats. The wood is strong, heavy, and hard. The wood is difficult to work due to its interlocked grain and somewhat difficult to finish due to its oily texture. Uses include posts, pilings, charcoalCharcoal
Charcoal is the dark grey residue consisting of carbon, and any remaining ash, obtained by removing water and other volatile constituents from animal and vegetation substances. Charcoal is usually produced by slow pyrolysis, the heating of wood or other substances in the absence of oxygen...
, and fuel
Firewood
Firewood is any wood-like material that is gathered and used for fuel. Generally, firewood is not highly processed and is in some sort of recognizable log or branch form....
. In spite of the fact the tree grows in a marine environment, the dry wood is subject to attack by marine borers and termite
Termite
Termites are a group of eusocial insects that, until recently, were classified at the taxonomic rank of order Isoptera , but are now accepted as the epifamily Termitoidae, of the cockroach order Blattodea...
s. Like many species, it contains tannin
Tannin
A tannin is an astringent, bitter plant polyphenolic compound that binds to and precipitates proteins and various other organic compounds including amino acids and alkaloids.The term tannin refers to the use of...
in the bark and has been used to tan
Tanning
Tanning is the making of leather from the skins of animals which does not easily decompose. Traditionally, tanning used tannin, an acidic chemical compound from which the tanning process draws its name . Coloring may occur during tanning...
leather
Leather
Leather is a durable and flexible material created via the tanning of putrescible animal rawhide and skin, primarily cattlehide. It can be produced through different manufacturing processes, ranging from cottage industry to heavy industry.-Forms:...
products.