Eugeissona

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Eugeissona
Eugeissona sp.

Eugeissona sp.

Systematics
Commelinids
Order : Palm- like arecales
Family : Palm family (Arecaceae)
Subfamily : Calamoideae
Tribe : Eugeissoneae
Genre : Eugeissona
Scientific name of the  tribe
Eugeissoneae
WJBaker & J.Dransf.
Scientific name of the  genus
Eugeissona
Handle.

Eugeissona handle. is a palm genus native to Southeast Asia. They are heavily reinforced palm trees that bloom only once, the fruits are densely covered with small scales. Eugeissona is the only genus of the tribe Eugeissoneae W.J.Baker & J.Dransf.

features

The representatives are multi-stemmed palms, with many spines . They bloom only once (are hapaxanth ), the species are polygamous . The trunk can be hidden underground and upright, or it stands on stilt roots and grows up to 3 m high. It is often branched at the base. The internodes are short to medium-long and mostly covered by rotting leaf sheaths. In tree-shaped species, the internodes become free and then sometimes form spiky adventitious roots . The stem bark is hard, the pulp is soft and contains large amounts of starch just before flowering .

The number of chromosomes is not known.

leaves

The leaves are pinnate and spiral or in three rows. The leaf sheath usually tears on the opposite side to the petiole . At the bottom it is unarmed, further up it has black, flattened spines and branched hair. The distal edge of the leaf sheath is similar to a ligule . The petiole is clearly pronounced, clearly furrowed on the upper side (adaxial). On the underside (abaxial) there are scattered to densely black, flattened spines, between these mostly scales and hair. The rachis is less densely reinforced than the petiole. The leaflets are simply folded, numerous, their outline is linear to lanceolate, the edge whole. Their arrangement is regular or they are grouped and fanned out within the group so that the leaf has a feathery appearance. Often there are small thorns along the main nerves and on the edge.

Inflorescences

The inflorescence stands upright and consists of branches that correspond to the lateral inflorescences of the pollakanthic palms. Each branch is four-fold and stands in the axilla of leaves with reduced blades or of tubular, unreinforced, brown bracts . The branches of each order have a tubular, double- keeled cover leaf and end in a cupula of brown, spiraling bracts that envelop a pair of flowers. A cupula consists of eleven to thirteen bracts. the one to three most proximal and distal ones each have an abortive side bud , the others are empty. The proximal five are tubular, the rest are open. The pair of flowers consists of a large male flower and an equally large hermaphrodite flower to the side of it. The male appears first and is then forced out of the cupula by the developing hermaphrodite.

blossoms

The flowers are among the largest among the palm trees. The male flowers are on a short flower stalk. The calyx is tubular, leathery, striped lengthways, dull brown and has three short, pointed lobes. The crown is tubular in the lower quarter to third and then has three narrow, long, woody, lobes standing on top of each other, which end in hard, sharp, spiky tips. There are 20 to 70 stamens that attach to the end of the corolla tube. The stamens are short and upright, the anthers are narrow, elongated, basifix and dull yellow to purple. They open latrors or intrors (on the side or on the inside). After flowering, they fall out. The stamp rudiment is very small. The pollen grains are ellipsoidal, bisymmetrical. The germ opening is distal and is a sulcus (germ groove). The longest axis is 41 to 73 micrometers long.

The hermaphrodite flowers are protandric , have no pedicel and have a double-keeled, leathery and tubular cover leaf . The flower is very similar to the male flower. Only the tip of the flower is flattened on the side where the bud was pressed in by the male flower. The calyx, crown and stamens also resemble the male flower. The ovary is columnar, consists of three carpels , has three ovules . The outside is covered with small scales. The scar is conical to pyramidal with three sides. The ovules are basal and anatropic.

fruit

The fruits are egg-shaped with a beak. At the top are the scar remains. Bracts, calyx and mostly also the crown remain on the fruit. The exocarp is covered with irregular vertical rows of very small scales. The mesocarp is to mature a little corky crossed and fiber bundles. The endocarp develops from a layer of cells outside the wall of the seed fan, is dark brown to black, very hard and thick, and sometimes connected to the fibers of the mesocarp. From the endocarp, 3 + 3 or 3 + 3 + 6 protrusions extend into the fruit cavity and form symmetrical, not completely separated areas. Only one seed is produced per fruit, this is attached to the base. It fills the fruit cavity and lies close to the endocarp, which means that it is pressed in through its protrusions. The seed coat is thin and dry, the endosperm is homogeneous, the embryo is basal.

Flower ecology

The flower ecology was only investigated in Eugeissona tristis . The flowers, and even more so the flower buds, produce large amounts of nectar. This is alcoholic due to the activity of different types of yeast. With a maximum ethanol concentration of 3.5%, nectar is one of the strongest naturally occurring alcoholic beverages. The mean value was 0.6%, the median 0.5%. The approximately 1000 flowers per inflorescence bloom synchronously. First, nectar is produced in the bud stage for around 38 days, then the male flowers bloom for one night, followed by 41.8 days of rest. This is followed by another 51 days of nectar production, two nights of pollen release, and another 20.9 days of nectar production before the scars are exposed and ready for conception. The flowers are visited by small mammals that feed on the nectar. Of the seven species, particularly frequent visitors are the feather-tailed pointed squirrel ( Ptilocercus lowii ) and the Sunda slowlory ( Nycticebus coucang ). These mammals are also believed to be responsible for pollination.

Distribution and locations

The representatives of the genus occur only on the Malay Peninsula and Borneo . The species found on Borneo grow on nutrient-poor soils. They are particularly noticeable on hilltops and steep slopes. Eugeissona minor and Eugeissona insignis also occur in low-lying heather forest called keranga. On the Malay Peninsula, the species grow on richer soils on hill slopes. Eugeissona tristis grows in a wide range of forest types, from swamp edges to hilltops, but it is most common on hills up to 1000 m above sea level. All species grow in large stocks, only no information is available about Eugeissona ambigua .

Systematics

The genus Eugeissona alone forms the tribe Eugeissoneae. This is within the subfamily calamoideae the sister group of all other calamoideae.

The genus consists of six species:

The name Eugeissona comes from the Greek and is made up of the words for good and roof . It refers to the use of the leaves to cover roofs.

use

From the tribes of Eugeissona utilis , the Penan people on Borneo gain strength similar to that of Sago . Also eugeissona insignis can be used that way. Roofs are made from the leaves of all kinds. Arrows for blowguns or toys are made from the petioles. The endosperm of young seeds is edible. Walking sticks are made from the stilt roots of Eugeissona minor .

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. 143-146.

Individual evidence

  1. ↑ Frank Wiens, Annette Zitzmann, Marc-André Lachance, Michel Yegles, Fritz Pragst , Friedrich M. Wurst, Dietrich von Holst, Saw Leng Guan, Rainer Spanagel: Chronic intake of fermented floral nectar by wild treeshrews . Proceedings of the National Academy of Sciences, Vol. 105, 2008, pp. 10426-10431. doi : 10.1073 / pnas.0801628105
  2. ↑ a b c d e f g Rafaël Govaerts (Ed.): Eugeissona. In: World Checklist of Selected Plant Families (WCSP) - The Board of Trustees of the Royal Botanic Gardens, Kew . Retrieved July 31, 2018.

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