Oncosperma

Oncosperma tigillarium

Oncosperma is a native to South and Southeast Asian palm species. The large, multi-trunked palms bear many spines and have feathery leaves.

• 5.1 Notes and references

Features

The representatives are large, usually multi-stemmed palm with spines. The species are monoecious getrenntgeschlechtig ( monoecious ). The stem is erect and often very high, Oncosperma tigillarium can reach a height of 24 m and more. Older parts of the stem are smooth, ringed by leaf scars. The spines are scattered up tight and are quite strong. They tend to decrease with increasing age. In one type, Oncosperma fasciculatum, the trunk sometimes branched above ground.

The chromosome number is 2n = 32 (± 2-4).

The leaves are pinnate. When leaves fall no residual remains. The leaf sheaths are Roehrig and form a distinct crown shaft, which is staffed with spines of different lengths. The petiole is usually strong and densely covered with spines. The leaflets are very numerous, simple folded, acute to acuminate, and mostly hanging. In Oncosperma fasciculatum they are in groups and in several layers.

Inflorescences

The inflorescences are single, between the leaves and are two-fold, more simply branched at the top of the base. You are protandrisch and stand erect in bud stage. The peduncle is short, broad and winged at the base. In its heyday, it is level. The straight spines are scattered up tight. The cover sheet is based directly on the peduncle base at, is robust, tubular, flattened, zweikielig, beaked and short coriaceous to woody. Until anthesis the cover sheet enveloping the inflorescence completely. There is a bract on peduncle, similar to the previous sheet, however, is less densely reinforced. The inflorescence axis is longer than the peduncle, it bears few to many related side branches of the first order. Your bracts are inconspicuous. The side branches are long, slender, hanging, bare and bear in a spiral arrangement of short triangular bracts, where are the flowers triads. At the ends of branches male flowers appear singly or in pairs.

Flowers

The male flowers are asymmetrical, or only short-stalked. The three sepals are pointed, keeled, overlapping, sometimes fused briefly below. The three petals are pointed or acuminate, much longer than the sepals and sometimes grow together briefly at the base. The six to nine stamens are shorter than the crown, the stamens are short, thick and sometimes fused basally into a short ring. The anthers are in the midst of the stamens attached ( Medifix ), at the lower end of an arrow shape, the pollen sacs are latrors. The stamp rudiment may be longer or shorter than the stamens. The pollen grains are ellipsoidal and symmetrical. The germ is opening a distal sulcus. The longest axis measures 27 to 43 microns.

The female flowers are more spherical. The three sepals are free, rounded, and overlapping. The three petals are free, rounded, overlapping at the base, top flap-like standing. The six staminodes are very small. The gynoecium is unicompartmental, has an ovule is spherical to ovoid. The scars are apically and are rarely noticeable. The orientation of the seed plant is unknown.

Fruits

The fruit is globose, dark blue - black, the scar remains standing sideways or subapical. The exocarp is smooth or pitted, the mesocarp is thin and fleshy and without fibers. The endocarp is thin, crusty and the seeds tightly. The seed has anastomose a long, lateral umbilical ( hilum ), the Raphe valve - branches. The endosperm is deeply grooved ( ruminat ). The embryo is subbasal. The primary leaf of the seedling is in two parts ( bifid ).

Dissemination and locations

The genus is widespread in South and Southeast Asia. A species is endemic to Sri Lanka, two species widely distributed in the Philippines, the two remaining species are in Southwest Asia and West Malaysia's reach and Sulawesi, the Philippines and the western Moluccas. Oncosperma tigillarium is a characteristic nature of the landward boundaries of mangrove forests. Oncosperma fasciculatum growing on steep slopes at 300 to 1000 m above sea level. The remaining three species grow domestically on hilly sites. All types usually grow in clusters and are very noticeable. They are common.

System

The genus Oncosperma is placed in the subfamily Arecoideae, Tribe Areceae, subtribe Oncospermatinae within the family Arecaceae. Within the subtribe she is the sister group of a clade with Deckenia, Acanthophoenix and Tectiphiala. The genus itself is monophyletic.

Govaerts and Dransfield accepted 2005 in World Checklist of Palms five types:

• Oncosperma fasciculatum
• Oncosperma gracilipes
• Oncosperma horridum
• Oncosperma platyphyllum
• Oncosperma tigillarium

Use

The palm heart of most species is palatable and is collected widely. The strains of Oncosperma tigillarium are very durable and have been used as a telegraph poles and as a material for floors. The leaf sheaths are sometimes used as baskets.

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. 567-570.