Tahina spectabilis
| Tahina spectabilis | ||||||||||||
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Tahina spectabilis |
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| Systematics | ||||||||||||
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| Scientific name of the genus | ||||||||||||
| Tahini | ||||||||||||
| J.Dransf. & Rakotoarin. | ||||||||||||
| Scientific name of the species | ||||||||||||
| Tahina spectabilis | ||||||||||||
| J.Dransf. & Rakotoarin. |
Tahina spectabilis is a species of palm family nativeto Madagascar . It is the only fan palm in Madagascar that flowers only once in a lifetime.
features
Tahina spectabilis is a single-stemmed, tree-shaped palm. The massive trunk is unreinforced and 4 to 10 m high. The base of the trunk is bulbous and the diameter at breast height is around 50 cm. The internodes are 8 to 10 cm long, the nodes 1.5 to 3.5 cm. The palms are hermaphroditic and bloom only once in a lifetime ( hapaxanthia ).
The number of chromosomes is unknown.
leaves
The leaves are fan-shaped, with the petiole extending a little into the blade , so the leaves are costapalmat. In young palms the dead leaves on the plant dry up, in individuals with a taller trunk they then fall off under their own weight. Adult palms have around 12 to 18 leaves. The leaf sheath is 80–100 × 52–58 cm and has a conspicuous crevice below the petiole. The petiole is massive, long, and covered with white wax. The top is deeply furrowed, the edge smooth. The length is 3.5 to 3.8 m, the diameter decreases from around 12 cm at the bottom to 6 to 8.5 cm at the top. The hastula on the upper side of the leaf is clear, the one on the underside hardly developed. The costa (the part of the stem protruding into the blade) is around 1.5 m long. The leaf blade has a diameter of 2.8 to 4.1 m. It is divided into multiple folded segments up to about half the radius. The number of segments is 110 to 122. These segments are in turn divided into less deeply incised, simply folded segments. The folding of these sub-segments is induplicate (V-shaped). The blade is bare and covered with a thin, white layer of wax on the underside of the leaf.
inflorescence
The inflorescence is above the leaves at the end of the stem. It is around 4 m long and consists of several inflorescences. Each of the partial inflorescences is triply branched. All lateral axes end in flower-bearing axes (rachillae).
The front page of the first-order side branch is double-keeled and empty. The bracts are conspicuous, Roehrig and usually quite, less often split. They are thickly covered with white hair. In each bract there is a second-order lateral axis.
The lateral axes of the second order carry a tubular, two-keeled cover sheet, which is some distance from the base. The bracts that follow are tubular, striped and covered with decrepit white coat. In each bract there is a third-order lateral axis. The basal side axes of the third order also have side axes of the fourth order.
The rachillae are straight, cylindrical and rather stiff. They have conspicuously distant, tubular, striped and bald bracts, each with a wrap of up to two flowers in their armpits.
blossoms
The flowers are hermaphroditic and have short stems. The three sepals are membranous and fused in the lower half. The calyx lobes are lanceolate with triangular tips. The three petals are fused at the base and connected to the receptaculum in such a way that both form a stem-like base. The free part of the petals are boat-shaped tips, the edges of which are usually rolled up. They are slightly hooded at the top. The six stamens have short filaments. The anthers are elongated, basifix and intrors. The gynoeceum consists of three intergrown carpels and contains three ovules . The ovary is pyramidal with edges and ridges, the pen is short and has three grooves that scar is not differentiated. The ovule type is not known.
The shape of the pollen is not known.
Fruits and seeds
The fruits are broadly ellipsoidal to obovate and measure 25–30 × 20–22 mm. They stand at the stem-like crown base. At the top of the fruit are the remains of the scars. The exocarp is smooth and bald, the mesocarp is moderately thick, spongy and has few fibers. The endocarp is thin, crust-shaped and has a clear longitudinal furrow and a short beak at the tip. The only spherical seed per fruit is 18 to 22 mm in size and has a heavily furrowed (ruminates) endosperm , it lacks a central cavity.
Distribution and locations
Tahina spectabilis is in one small area in the northeast of Madagascar , in the district Analalava, endemic . The area is close to the coast at a few meters above sea level. Here there are hills made of tertiary limestone known as tsingy , which - located in the midst of anthropogenic grassland - still have semi-natural vegetation. There is hardly any fertile soil here, the vegetation consists of low woodland, which is characterized by xerophytes and succulents , including representatives of the genera Euphorbia , Aloe and Kalanchoe . From Tahina spectabilis are only 90 individuals known (as of 2012), most of which grow on the sandstone layer at the edge of the tsingy . The plain is characterized by an herbaceous savannah in which there are numerous specimens of the palm species Hyphaene coriacea . Here the moisture is significantly more favorable due to the other subsurface.
The area has an annual rainfall of around 1,600 mm, but the dry season lasts eight months. The annual average temperature is around 27 ° C. Further inland, the average and minimum temperatures drop significantly, which means that the probability of finding the species there is classified as extremely low.
Systematics
The genus Tahina is placed within the family Arecaceae in the subfamily Coryphoideae , tribe Chuniophoeniceae . Her sister genus is Kerriodoxa .
In the World Checklist of Selected Plant Families of the Royal Botanic Gardens, Kew, only the species Tahina spectabilis is recognized.
The name Tahina means “blessed” or “protected” in Malagasy. The daughter of the discoverer of the species is called Anne-Tahina Metz, after her the genus was named. In Madagascar, the palm is called dimaka along with several more common species , so it does not have a name of its own. The palms were first sighted in 2005, but at that time they were kept as a representative of the genus Borassus , which is similar to the species in its vegetative state. In September 2006, the palm trees were photographed in bloom by the couple Xavier and Nathalie Metz. When they uploaded the photos to the homepage of the International Palm Society, John Dransfield of the Royal Botanic Gardens, Kew was made aware of the photos, who recognized them as new to Madagascar, most likely Corypha . An expedition by Mijoro Rakotoarinivo in the beginning of 2007 brought clarity, which was able to collect herbarium material including an infructescence as well as material for DNA analyzes. Even the morphological features put the finds in the tribe Chuniophoeniceae. Numerous morphological features as well as molecular genetic studies showed that the establishment of a new genus was appropriate. The first description was in 2008 by Dransfield and Rakotoarinivo.
supporting documents
- John Dransfield, Natalie W. Uhl, Conny B. Asmussen, William J. Baker, Madeline M. Harley, Carl E. Lewis: Genera Palmarum. The Evolution and Classification of Palms . Second edition, Royal Botanic Gardens, Kew 2008, ISBN 978-1-84246-182-2 , pp. 294-296.
- John Dransfield, Mijoro Rakotoarinivo, William J. Baker, Ross P. Bayton, Jack B. Fisher, James W. Horn, Bruno Leroy, Xavier Metz: A new Coryphoid palm genus from Madagascar . Botanical Journal of the Linnean Society, Volume 156, 2008, pp. 79-91. doi : 10.1111 / j.1095-8339.2007.00742.x
Individual evidence
- ↑ Rafaël Govaerts (ed.): Tahina. In: World Checklist of Selected Plant Families (WCSP) - The Board of Trustees of the Royal Botanic Gardens, Kew . Retrieved April 1, 2011.
Web links
- Tahina spectabilis inthe IUCN 2013 Red List of Threatened Species . Posted by: Rakotoarinivo, M. & Dransfield, J., 2012. Retrieved September 19, 2013.