The black mangrove (Avicennia germinans L.) is a shrub or perennial tree of small size that belongs to the Acanthaceae family. This species is distributed from the southern United States to Panama, as well as western South Africa and India.
On average, the black mangrove is 5 meters tall with a stem that has a diameter of 20 to 60 cm. The roots of this mangrove are superficial and some are differentiated into pneumatophores.
Avicennia germinans. Codiferous at the English language Wikipedia
Meanwhile, the leaves are arranged in the opposite way and vary in size. Each can be 3 to 12 cm long by 1 to 4 cm wide. In addition, each leaf hangs from a thick petiole that measures 1.3 cm.
The adaxial surface of the leaves has a shiny appearance with a smooth texture, while the underside is pale with much pubescence. The flowers are arranged in axillary inflorescences, which are 2 to 6 cm long.
The black mangrove is used as an agroforestry resource and in traditional medicine, since it has astringent, anti-hemorrhagic, anti-malarial, anti-diarrheal properties, among others.
characteristics
The black mangrove is an evergreen tree or shrub native to the state of Florida, being monoecious and measuring 2 to 8 meters high. The stem of this tree is thick, 20 to 60 cm wide, with dark brown bark, which has irregular, flattened and rough scales.
This species has superficial roots and also develops modified roots to capture oxygen in flooded environments, called pneumatophores.
Pneumatophores. Ulf Mehlig
The leaves of the black mangrove are elliptical in shape and arranged in an opposite way; they are thick with a leathery consistency and have glands in the apical end. Each leaf is 3 to 15 cm long by 1 to 4 cm wide and hangs from a thick petiole 1.3 cm long.
Black mangrove leaves. Ulf Mehlig
The flowers are arranged in axillary inflorescences, which are 2 to 6 cm long. In turn, the flowers are sessile with a width of 1 to 2 cm. The petals develop a tube 0.3 to 0.4 cm long and are greenish, cream or white in color. The four stamens are 0.4–0.5 cm long, while the style is 0.1–0.3 cm long.
Meanwhile, the fruits are 2 to 3 cm in diameter, flat, dark green and with a velvety pericarp.
Taxonomy
- Kingdom: Plantae.
- Subkingdom: Viridiplantae.
- Infra kingdom: Streptophyte.
- Super division: Embriofita.
- Division: Tracheophyte.
- Subdivision: Eufilofitina.
- Infra division: Lignofita.
- Class: Spermatophyte.
- Subclass: Magnoliofita.
- Superorder: Asteranae.
- Order: Lamiales.
- Family: Acanthaceae.
- Subfamily: Avicennioideae.
- Genus: Avicennia.
- Species: Avicennia germinans.
The genus Avicennia (L.) was from the beginning within the Verbenaceae family, however it was later introduced by botanical proximity to the Avicenniaceae family.
However, by molecular studies the genus has been found to be close to the Acanthaceae family. The genus has been classified into two geographical areas, new and old world. In this case, A. germinans has a distribution in the New World, being considered one of the largest species of Avicennia.
Habitat and distribution
In natural areas, the black mangrove inhabits woody formations that are located at an altitude of 0 to 15 meters above sea level. It adapts to a variety of climatic conditions ranging from tropical rainy climates to semi-arid or arid climates.
Avicennia germinans frequents the shores of coastal water bodies, bays, and river mouths. It can also colonize swamps that do not suffer from flooding and with low levels of salt.
This species of mangrove responds to a salinity gradient, coexisting with other mangrove species when the salinity ranges between 30 to 40 parts per thousand, while if the salinity is greater than or equal to 50 parts per thousand, the black mangrove is the species dominant.
Dwarf trees on smooth hypersaline mud. Ulf Mehlig
From an ecological point of view, the black mangrove constitutes the basic diet of many species of birds and mammals. This undoubtedly brings socio-economic benefits, since mangroves as an ecosystem provide at least 1.6 trillion dollars annually, directly or indirectly.
Avicennia germinans is the most distributed Avicennia species in the New World, from southeastern North America, Bermuda, the West Indies, Central America, South America, and tropical west Africa.
It is regularly associated with Allenrolfea occidentalis, Batis maritima, Bravaisia berlandieriana, Coccoloba uvifera, Conocarpus erectus, Distichlis littoralis, Echinochloa polystachya, Frankenia palmeri, Laguncularia racemosa, Maytenus phyllanthoides, Rhizophora bilayeviii, and Salicorni bilapartiflora mangle, Salicorni bilapartiflora alterniflora, and Pligelovumina pligeloevila.
The black mangrove is the mangrove species with the greatest distribution to the north, being limited by the cold temperatures, which can cause mortality to this species. In recent times, this species has been distributed further north due to changes in temperature that have made winters last shorter.
Applications
The black mangrove is used by local people as firewood, for building materials or for fences. Likewise, it has been used in traditional medicine for its astringent, anti-hemorrhagic, antimalarial, antidiarrheal, anticancer properties, and it is also used in the treatment of hemorrhoids, rheumatism, swelling, etc.
Components such as the naphthoquinone 3-chloro oxylapacol, which has been isolated from A. germinans leaves, have shown anticancer properties. For its part, the bark of the black mangrove is used to promote the birth of children and is used as a topical to treat skin conditions.
In turn, the resin from the bark is used in traditional medicine to treat tumors, diarrhea, hemorrhages, hemorrhoids, rheumatism, swelling and wounds. The bark is also used as a colorant, since it contains about 12.5% tannins.
Meanwhile, Avicennia germinans wood is used for marine constructions, as it has a very hard structure, even under water, and a very fine texture.
It is used to build boats, docks, piles, furniture, and implements. It is also useful for heavy floors, mine accessories, vehicle bodies, etc.
References
- CONABIO. 2009. Black mangrove. Mexican Species Sheets. National Commission for the Knowledge and Use of Biodiversity. Mexico, DF, Mexico. Compiled by Elizabeth Torres Bahena; Reviewed by Carlos Galindo Leal. March 2009.
- Perry, CL, Mendelssohn, IA 2009. Ecosystem effects of expanding populations of Avicennia germinans in a Louisiana salt marsh. Wetlands, 29 (1), 396–406.
- Sobrado, MA 1999. Leaf photosynthesis of the mangrove Avicennia germinans as affected by NaCl. Photosynthetica, 36 (4), 547–555.
- Suárez, N., Medina, E. 2005. Salinity effect on plant growth and leaf demography of the mangrove, A vicennia germinans L. Trees, 19 (6), 722–728.
- Daniel, TF 2016. Avicennia (Acanthaceae: Avicennioideae) in North America and Mesoamerica. Proceeding of the California Academy of Science, 63 (5): 163-189.
- Hrudayanath, T., Dibyajyoti, S., Swagat KD 2016. The genus Avicennia, a pioneer group of dominant mangrove plant species with potential medicinal values: a review. Frontiers in Life Science, 9 (4): 267-291.
- The Taxonomicon. (2004-2019). Taxon: Genus Avicennia L. (1753) (plant). Taken from: taxonomicon.taxonomy.nl.