Oncosperma

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Oncosperma
Oncosperma tigillarium

Oncosperma tigillarium

Systematics
Commelinids
Order : Palm- like arecales
Family : Palm family (Arecaceae)
Subfamily : Arecoideae
Tribe : Areceae
Genre : Oncosperma
Scientific name
Oncosperma
flower

Oncosperma is a genus of palm that is native to South and Southeast Asia. The large, multi-stemmed palm trees have many spines and pinnate leaves.

features

The representatives are large, mostly multi-stemmed palms with spines . The species are single sexed ( monoecious ). The trunk is upright and often very tall, Oncosperma tigillarium can reach a height of 24 m and more. Older trunk parts are smooth, curled by leaf scars. The spines are scattered to close and are quite strong. They tend to fall off with age. In one species, Oncosperma fasciculatum , the trunk sometimes branches above ground.

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

leaves

The leaves are pinnate. When the leaf falls, no residue remains. The leaf sheaths are tubular and form a distinct crown shaft, which is covered with spines of different lengths. The petiole is usually strong and densely covered with spines. The leaflets are very numerous, simply folded, pointed to pointed, and mostly drooping. In Oncosperma fasciculatum they are in groups and on several levels.

Oncosperma tigillarium with inflorescence

Inflorescences

The inflorescences are single, between the leaves and are twofold at the base, but only simply branched further up. They are protandric and stand upright in the bud stage. The peduncle is short, wide and winged at the base. In the heyday it stands horizontally. The straight spines are scattered to close together. The cover sheet starts directly above the base of the inflorescence stalk, is robust, tubular, flattened, double-keeled, short beaked and leathery to woody. The cover sheet completely envelops the inflorescence up to the anthesis . There is a bract on the peduncle, which is similar to the previous leaf, but is less densely reinforced. The inflorescence axis is longer than the stalk, it bears a few to many hanging side branches of the first order. Their bracts are inconspicuous. The side branches are long, slender, drooping, glabrous and in a spiral arrangement they have short triangular bracts in which the flower triads are located. Male flowers stand solitary or in pairs at the branch ends.

blossoms

The male flowers are asymmetrical, with no or only short stalk. The three sepals are pointed, keeled, overlapping, sometimes briefly fused below. The three petals are pointed or pointed, much longer than the sepals and sometimes briefly fused at the base. The six to nine stamens are shorter than the crown, the stamens are short, thick and sometimes fused together to form a short ring at the base. The anthers are attached to the filament in the middle (medifix), arrow-shaped at the lower end, the pollen sacs are latrors . The rudiment of the pistil can be longer or shorter than the stamens. The pollen grains are ellipsoidal and symmetrical. The germ opening is a distal sulcus . The longest axis measures 27 to 43 microns.

The female flowers are rather spherical. The three sepals are free, rounded and overlapping. The three petals are free, rounded, overlapping at the base, standing like flaps at the top. The six staminodes are very small. The Gynoeceum is single-faced, has an ovule , is spherical to ovoid. The scars are apical and are rarely noticeable. The orientation of the ovule is not known.

fruit

The fruit is spherical, dark blue-black, the remnants of the stigma are lateral or subapical. The exocarp is smooth or pitted, the mesocarp is thin and fleshy and without fibers. The endocarp is thin, crust-like and tightly fitting to the seed. The seed has a long, lateral umbilicus (hilum) that anastomose raphenous branches . The endosperm is deeply furrowed (ruminate). The embryo is subbasal. The primary leaf of the seedling is in two parts (bifid).

Distribution and locations

The genus is common in South and Southeast Asia. One species is endemic to Sri Lanka , two species in the Philippines , the other two species are widespread in Southwest Asia and West Malesia and reach Sulawesi , the Philippines and the western Moluccas . Oncosperma tigillarium is a characteristic species of the landside border of mangrove forests. Oncosperma fasciculatum grows on steep slopes at 300 to 1000 m above sea level. The other three species grow inland on hilly locations. All species usually grow in groups and are very showy. They are common.

Oncosperma tigillarium , Botanical Garden in Peradenia, Sri Lanka

Systematics

The genus Oncosperma flower is placed within the family Arecaceae in the subfamily Arecoideae , Tribe Areceae , Subtribus Oncospermatinae. Within the subtribe it is the sister group of a clade with ceilingia , acanthophoenix and tectiphiala . The genus itself is monophyletic .

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

use

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

literature

  • 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.

Individual evidence

  1. ^ Robert Lee Riffle, Paul Craft: An Encyclopedia of Cultivated Palms , 4th Edition, Timber Press, Portland 2007, ISBN 978-0-88192-558-6 , p. 396.
  2. ↑ Rafaël Govaerts (ed.): Oncosperma. In: World Checklist of Selected Plant Families (WCSP) - The Board of Trustees of the Royal Botanic Gardens, Kew . Retrieved August 7, 2018.

Web links

Commons : Oncosperma  - collection of images, videos and audio files
  • Oncosperma on the homepage of the Fairchild Tropical Botanic Garden