Avicennia germinans
Syn. Bontia germinans, Avicenna nitida, Avicenna tomentosa, Avicennia africana

Names: Black Mangrove, White Mangrove,  bwadmèch, black mangrove, white mangrove, olive mangrove, mangle bobo, mang blan, wood wick, mangle white, false mangrove, mang gri, gray mangrove, china de vaca, prieto, salado, mangle nero, Mango amarelo…

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FAMILY

ACANTHACEAE

 

ETYMOLOGY

Avicennia comes from Ibn Sina, Arab philosopher and doctor and germinans "germination, budding". Tropical America .

 

ORIGIN

Tropical America.

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HABITAT

Low mangrove and high mangrove.

 

DESCRIPTION

This tree occupies the internal part of the mangrove, the old subjects have a rather slender port  and can  measure 20-25m high.
The trunk, branches and twigs have a gray or brownish bark, marked with leaf scars as well as barely visible aerial roots. The heartwood is pale brown to pinkish brown, often darkening upon exposure, and indistinctly demarcated from the whitish sapwood. It often presents an interlocked grain, the grain is fine.
The wood is heavy, with a density of around 950 kg/m³ at 12% moisture content. 
The leaves are opposite, 8 to 15cm long, leathery, elongated and pointed. The upper side is green and shiny while the underside is paler and fluffier. 
Flowering is manifested by terminal inflorescences of white corolla flowers having 4 petals. 
The fruits are compressed, ovoid, measure 12 to 20mm and are grey-green to yellow. A thin film (the pericarp) surrounds the seed. It is carried away by currents and tides. The fruit will open after a period of floating resembling a small vessel, the root will begin to grow until it encounters a shallower place where it can flourish.
On the ground, the pneumatophores (air roots) are thin, vertical, elongated and very numerous. They allow it to breathe and colonize muddy environments that are therefore poor in oxygen.
The black mangrove is a pantropical species .

 

NEEDS

Heavy watering .
Soil: Draining. 
Exposure: Full sun as an adult.
Hardiness: 9-11. 
Flowering: Mainly from April to August.
Fruiting: April to October.

 

MULTIPLICATION

Seeds, cuttings 
- A period of flotation is necessary for the germination of the seeds. 
- You can use a mini-greenhouse or a transparent plastic bag half filled with water and perlite (optional)
- Floating can last two weeks.
- A heating mat and a lamp will be necessary depending on your latitudes.
- Once the seeds are open, wait for the roots to develop a little.
- Then transplant into a draining substrate.

 

CULTURE

Draining substrate in a cup of water, full sun. It likes heat and humidity.
For the Black Mangrove, the obligatory fruit floating period is shorter than that of the White Mangrove. 
Thanks to its pneumatophores, the black mangrove withstands temporary flooding. It tolerates the most salty and asphyxiating soils.

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MAINTENANCE
- An organic amendment and regular watering is recommended.
- It is an easy plant to grow and maintain.
- Prune the branches that cross each other.

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USES
 

MEDICINAL USE

Invalid.
The bark contains about 12.5% tannin. An extract of leafy twig of Avicennia germinans from South Florida (USA) showed cytotoxic activity against several human cancer cell lines, a naphthoquinone, 3-chlorodeoxylapachol, being the active compound.

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ORNAMENTAL USE

Very nice indoor plant. Can be planted as an isolated subject or in a rocky bed.
 

FOOD USE

The seed cotyledons are eaten in times of famine, but only after careful preparation to eliminate toxins.
The leaves and roots are used to prepare vegetable salt.

 

OTHER USES

It is planted to secure coastal ecosystems thanks to its high resistance to salt and waves.
The wood is used for the frames of the boats, the carpentry, the stays, the chrono and the smoking of the fish.
The bark is used for tanning and as a red dye.
The flowers are a source of nectar for bees.

 

ANECDOTES

The wood smoke would effectively repel mosquitoes. 
It is a very durable wood, even when covered with water, and resistant to termite and Lyctus attack.
Ethanol solutions of wood smoke from burning Avicennia germinans blocked the growth of pathogenic bacteria and fungi, such as Escherichia coli , Staphylococcus aureus , and Saccharomyces cerevisiae , which helps support the idea that the wood is effective for smoking fish and other foods. On the other hand, the smoke notably prevented Acraea acerata , a pest of sweet potato, from laying its eggs.

 

Black Mangrove Adaptation Strategies

The pneumatophores are branches of the root system which rise above the surface of the soil and develop more or less in the open air. Those of the Black Mangrove are straight and elongated. They have lenticels through which gas exchange takes place.
They also have a specialized tissue, the aerenchyma, which is able to store air inside these pneumatophores thanks to gaps.
These pneumatophores therefore have a triple ecophysiological function: Respiratory function, Absorption function, Synthesis function of these two roles. 
In the black mangrove, the passage of salt is free and even accelerated at leaf level, either by excretory glands or by stomata. Once excreted, the salt crystallizes on the surface of the leaf. Abundant transpiration at the leaf level allows strong suction to develop which also contributes to the evacuation of salt.
However, each species has its own optimum salinity which, if exceeded, causes an increase in respiration, a phenomenon which is the cause of poor plant growth.
Each species therefore occupies the salinity zone to which it is best adapted, which generates the "metabolic base of zonation".

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SOURCES

• Illustrated flora of the phanerogams of Guadeloupe & Martinique - Jacques Fournet - Ed Gondwana, CIRAD
• The mangroves of the Antilles - Sylvétude ONF Guyane
• The mangrove and swamp forest of the West Indies - PLB Edition
• Plants, habitats and landscapes of the French West Indies - Parthénope collection

• https://www.prota4u.org/database/protav8.asp?fr=1&g=pe&p=Avicennia+germinans+(L.)+L.