Avicennia
Blossoming branch of the Black Mangrove ( Avicennia germinans )
Avicennia is the only plant genus of the subfamily Avicennioideae within the family of Acanthaceae ( Acanthaceae ). The genus is named after the Persian philosopher Avicenna.
The species of the genus Avicennia, in addition to not more closely related taxa of the tribe Rhizophoreae in the family of Rhizophoragewächse ( Rhizophoraceae ) the main mangrove trees. They are found in the sphere of influence of the tides tropical and subtropical coasts of all continents. The American-West African species Avicennia germinans is sometimes referred to as Black Mangrove, Avicennia marina, the Indo-Pacific as a Grey or White Mangrove; the name of White Mangrove, however sometimes for unrelated with Avicennia species Laguncularia racemosa (wing seed plants, Combretaceae ) is used.
In the Malay language as the tree api api is known, which means in the language of the Bajau "fire"; a reference to the fact that often collect swarms of fireflies in the trees.
- 4.1 Notes and references
Description
Vegetative characteristics
Avicennia species grow as trees or shrubs in the sphere of influence of the tides. The plants reach heights of growth of more than 30 meters. Characteristic are the breathing roots ( Pneumatophore ) perpendicular grow from underground root system upward and break through the soil surface. About air-permeable pores in the bark of the respiratory roots can reach the oxygen underserved, underground areas of the root system oxygen-rich air via a sponge-like air tissue ( aerenchyma ).
The wood of Avicennia shows ring structures formed by anomalous secondary growth. These rings do not meet the annual rings of trees in temperate zones. The Kambiumring forms on the inside of xylem parenchyma cells outside. One to three rows of cells within the outermost parenchyma cells, a ring of sclereids, which is also one to three rows of cells forming thick. The cambium is after a certain time his activity in Parenchymbereich within the Sklereidrings to phloem cells differentiate. After that forms outside the Sklereidrings a new Kambiumring. The branches are round in cross section, fresh shoots are sometimes square.
The arranged opposite, stalked leaves are undivided and entire. On the underside of leaves are densely covered with microscopic hairs. The leaf surface bears salt glands through which the salt content of the leaf tissue is regulated.
Generative features
The terminal aged men or capitate inflorescences bear dekussiert standing flower pairs. For each flower are a very small, curved bract and two scale-like bracts. The sessile, small flowers are four - or fünfzählig and have a double perianth. The five sepals are fused short cup-shaped at the base, the sepals overlap laterally. Bract, bracteoles and sepals remain to fruit maturity. The whitish or yellowish - reddish petals are slightly zygomorphic at the bottom of a intergrown bell-shaped corolla tube; the upper one of the four ( in some cases, five) Kronlappen is often wider than the rest. It's just a circle with four stamens present, the start at the top of the corolla tube. The four carpels are fused into a superior ovaries. Inside, he carries four hanging ovules, of which only one develops. The flowers are nectar rich and are pollinated by insects.
The fruits are classified by some authors as leathery capsule fruits, other than achene. The seeds are still developing at the nut tree seedlings, but these remain in the fruit which will burst soon after it was dropped and the buoyant seedling releases ( " crypto- viviparous ," hidden - viviparous ).
System
The first publication of the genus name was in 1753 by Linnaeus in Species Plantarum, 1, pp. 110-111 with the type species Avicennia officinalis L.
The systematic position of Avicennia has long been controversial. Traditionally, the genus in the family of the verbena family ( Verbenaceae ) was arranged last but usually regarded as a separate family Avicenniagewächse ( Avicenniaceae ). Recent molecular genetic studies back Avicennia in the relationship of the Acanthaceae sensu lato, but confirm the monophyly of the group. After APWebsite Avicennia is the only genus in the subfamily Avicennioideae within the family of Acanthaceae ( Acanthaceae ).
The genus Avicennia comprises about eight to 14 species (selection):
- Avicennia alba Blume: Indo-Pacific from India to northern Australia
- Avicennia bicolor Standlschmaus. Central America
- Black Mangrove ( Avicennia germinans (L.) L. ): West Africa ( Syn: Avicennia africana P.Beauv, Avicennia nitida Jacq.. ), North and South America from the Bahamas to Brazil's Northeast
- Avicennia integra N. C. Duke
- Avicennia lanata Ridley: Malaysia
- Avicennia marina ( Forssk. ) Vierh. Indopazifik, north to the Sinai, south to New Zealand.
- Avicennia officinalis L.: southern India to eastern Australia.
- Avicennia rumphiana Hallier f
- Avicennia schaueriana Stapf & Leechman ex Moldenke: Atlantic coast of tropical South America and West Indies.
Among the species names mentioned there are a number of synonyms; some forms of very variable Avicennia marina were described as a distinct species.
Pictures
Avicennia marina var resinifera:
Branches with fruits.
Avicennia germinans:
Secreted by the activity of the salt glands of salt crystallizes on the leaf surface.
Detail of trunk cross section with Parenchymringen.
Swell
- Acanthaceae with the subfamily Avicennioideae in APWebsite. ( Section systematics)
- AE Schwarzbach, LA McDade: Phylogenetic relationships of the mangrove family Avicenniaceae based on chloroplast and nuclear ribosomal DNA sequences. In: Systematic Botany, 27 (1 ), 2002, pp. 84-98.
- Shou- liang Chen & Michael G. Gilbert: Verbenaceae in the Flora of China, Volume 17, 1994, p 49: Online. ( Description section )
- NC Duke: A systematic revision of the mangrove genus Avicennia ( Avicenniaceae ) in Australasia. In: Australian Systematic Botany, 4, 1991, pp. 229-334.
- PB Tomlinson. The Botany of Mangroves, Cambridge University Press, Cambridge 1986 419 pages. ISBN 0-521-46675- X: Google -book online.