Avicennia germinans

Avicennia germinans
Black Mangrove growing in Guanacaste Province, Costa Rica
Conservation status
Least Concern (IUCN 3.1)
Scientific classification
Kingdom:	Plantae
(unranked):	Angiosperms
(unranked):	Eudicots
(unranked):	Asterids
Order:	Lamiales
Family:	Acanthaceae
Genus:	Avicennia
Species:	A. germinans
Binomial name
Avicennia germinans (L.) L.
Synonyms
Avicennia africana P.Beauv. Avicennia nitida Jacq. Bontia germinans L.

Black mangrove (Avicennia germinans), is a species of flowering plant in the acanthus family, Acanthaceae.

A free-standing black mangrove tree growing in shallow water in the backcountry of the Cape Sable area of Everglades National Park.

A. germinans grows in tropical and subtropical regions of the Americas, on both Atlantic and Pacific coasts, and on the Atlantic coast of tropical Africa, where it thrives on the sandy and muddy shores that seawater reaches. It can grow to heights of 15 m (49 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. Seeds 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 surges, trap debris and detritus brought in by tides, and provide feeding, breeding, and nursery grounds for a great variety of fish, shellfish, birds, and other wildlife.

Habitat

The black mangrove grows just above the high tide in coastal lagoons and brackish water estuaries. It is less tolerant of highly saline conditions that certain other species that occur in mangrove ecosystems. It can reach 10–15 m (33–49 ft) in height, although it is a small shrub in the northern (colder) extent of its range. The seeds germinate 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, charcoal, 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 termites. Like many species, it contains tannin in the bark and has been used to tan leather products.

See also

• List of honey plants
• Mangrove ecoregions

References

• Haehle, Robert (1999). Native Florida Plants. Houston: Gulf Publishing Company. ISBN 0-88415-425-4. 

External links

Media related to Avicennia germinans at Wikimedia Commons

• Interactive Distribution Map of Avicennia germinans

Data related to Avicennia germinans at Wikispecies