Eugeissona

Eugeissona sp.

Eugeissona is a Native to Southeast Asia palm genus. There are heavily reinforced, only once flourishing palm trees, the fruits are densely covered with small scales. Eugeissona is the only genus of the tribe Eugeissoneae.

• 6.1 Notes and references

Features

The representatives are multi-stemmed palm, with many spines. They bloom only once ( are hapaxanth ), the species are polygamous. The trunk can be hidden underground and erect, or are on stilt roots and is up to 3 m high. He is often branched basally. The internodes are short to medium in length and usually hidden by rotting leaf sheaths. For tree-like species, the internodes are free and then sometimes spine-like protrusions form adventitious roots. The stem bark is hard, the marrow is soft and contains just before flowering large amounts of starch.

The number of chromosomes is not known.

The leaves are pinnate and are spirally or in three rows. The leaf sheath tears usually on the opposite side of the petiole. She is unarmed at the bottom, above she wears black, flattened spines and branched hairs. The distal edge of the leaf sheath is similar to a ligule. The petiole is pronounced clearly furrowed on the upper surface ( adaxial ). On the lower ( abaxial ) sit scattered to dense black, flattened spines, usually between these scales and hair. The rachis is less densely armed than the petiole. The leaflets are simply folded, numerous, their outline is linear to lanceolate, the margin quite. Their arrangement is regularly or they are grouped and wide within the group so that the sheet gets a fiedriges appearance. Along the main nerves and on the edge there are often small thorns.

Inflorescences

The inflorescence is upright and consists of branches that correspond to the lateral inflorescences of pollakanthen palms. Each branch is branched four times and is in the axil of leaves with reduced spreading or tubed, unreinforced, brown bracts. The branches of each order wear a röhriges, zweikieliges cover page and end in a cupula ( cup) of brown, spirally standing bracts that envelop a couple flowers. A cupula consists of eleven to 13 bracts. which each one to three proximal and distal possess an abortive lateral bud, the rest are empty. The proximal five are Roehrig, the other open. The flowers pair consisting of a large male and sides of her as great a hermaphrodite flower. The male appears first and is then forced by the developing hermaphrodite from the cupula.

Flowers

The flowers are one of the largest among the palm trees. The male flowers are on a short peduncle. The cup is Roehrig, leathery, longitudinally striped, dull brown and has three short, tipped lobes. The crown is Roehrig in the lower quarter to one-third and then has three narrow, long, woody, klappig successive projecting tabs which terminate in hard, sharp, spike-like peaks. There are 20 to 70 stamens, the schedule at the end of the corolla tube. The stamens are short and erect, the anthers are narrow, oblong, basifix and dull yellow to purple. They open latrors or intrors (side or on the inside ). After flowering, they fall out. The stamp rudiment is very small. The pollen grains are ellipsoidal, bisymmetrical. The germ is opening distally and is a sulcus ( seed furrow ). The longest axis is 41-73 microns long.

The hermaphrodite flowers are protandrisch have no flower stalk and have a zweikieliges, leathery and röhriges cover page. The flower is very similar to the male flower. Only the tip of the flower is flattened on the side on which the bud has been pressed from the male flower. Calyx, corolla 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 sit basal and are anatrop.

Fruits

The fruits are ovoid with a beak. At the top are the scars residues. Bracts, sepals and usually also the crown remain on the fruit. The exocarp is busy with irregular vertical rows of very small scales. The mesocarp is somewhat corky attracted by the maturity and fiber bundles. The endocarp develops from a cell layer outside the seed trays wall is dark brown to black, very hard and thick, and sometimes associated with the fibers of the mesocarp. From the endocarp rich 3 3 or 3 3 6 projections into the amniotic cavity and form symmetrical, not completely separate areas. Per fruit produced only one seed, this is attached basally. He fills the amniotic sac and is close to the endocarp, which he is pressed by its projections. The seed coat is thin and dry, the endosperm is homogeneous, the embryo is located basally.

Flowers Ecology

The flowers ecology has been studied only in Eugeissona tristis. The flowers, more particularly on the flower buds form large quantities of nectar. This is alcoholic by the activity of different yeast species. With a maximum ethanol concentration of 3.5 % of the nectar is one of the strongest naturally occurring alcohol. The mean value was 0.6 %, with a median of 0.5%. The approximately 1,000 flowers per inflorescence bloom synchronously. First, nectar is produced in the bud stage for about 38 days, then bloom for one night the male flowers, followed by 41.8 days rest. Then again follow 51 days of nectar production, two nights pollen release, again 20.9 days nectar production before the scars exposed and are ready to conceive. The flowers are visited by small mammals that feed on the nectar. Of the seven species particularly frequent visitors are the feather -tailed shrews ( Ptilocercus lowii ) and the Sunda slow loris ( Nycticebus coucang ). These mammals are likely to be responsible for pollination.

Dissemination and locations

The representatives of the genus are found only on the Malay Peninsula and Borneo. The occurring on Borneo species grow on poor soils. Particularly striking are on hilltops and steep slopes crashes. Eugeissona minor and Eugeissona insignis also occur in low-lying heath forest which is called keranga. In the Malay Peninsula the species grow on richer soils on hill slopes. Eugeissona tristis grows in a wide range of forest types, from marsh edges up to the hilltops, the highest frequency it has, however, on hills up to 1000 m above sea level. All species grow in large flocks, only about Eugeissona ambigua is no information available.

System

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:

• Eugeissona ambigua, Borneo, only the type known
• Eugeissona brachystachys, on the Malay Peninsula
• Eugeissona insignis, Borneo
• Eugeissona minor, Borneo
• Eugeissona tristis, on the Malay Peninsula
• Eugeissona utilis, Borneo

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

Use

From the tribes of Eugeissona utilis the Penan people gain on Borneo strength similar to tapioca. Also Eugeissona insignis can be used. From the leaves of all species roofs are manufactured. From the petioles Arrows for Blowgun or toys are manufactured. The endosperm of young seeds is edible. From the stilt roots of Eugeissona minor walking sticks are made.

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.