Pogonotium
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| J.Dransf. |
Pogonotium is a genus of palm native to Southeast Asia.
features
The representatives are reinforced, slender, single or multi-stemmed palms that grow upright or climb short. They are multiple flowering, dioecious, separate-sex ( diocese ) palms. The trunk has short internodes .
The number of chromosomes is unknown.
leaves
The leaves are pinnate and have no tendrils . The leaf sheath is tubular and densely covered with whorled or scattered spines and a fur felt. The sheath ends in two upright, narrow auricles, one on each side of the petiole . One knee is missing or barely developed. A flagellum is also missing. The petiole is clearly formed and filled by rearward facing barbs, as well as reinforced the rachis . The few to very numerous leaflets are linear, simply folded and regularly arranged. Its surface is covered with various bristles and scales. The central ribs stand out clearly on the underside.
Inflorescences
The inflorescences are in leaf axils, but are fused with the internode and the leaf sheath of the following leaf. They stand upright between the two little ears of the bract and are almost sitting. The female inflorescences are twofold, the male three-fold. The cover sheet includes the inflorescence, is boat-shaped with a flattened beak. It is reinforced or unreinforced and tears lengthways along the central adaxial or abaxial line, thus exposing the flowers. The bracts on the inflorescence axis are much smaller than the previous leaf. Your tips are free. In each axilla of the bracts as well as the front sheet there is a lateral axis. The bracts of the lateral axes of the first order are tubular at the base and have triangular branches.
blossoms
The male flowers are individually in an approximately disticher (two-line) arrangement on the branches of the second or third order. Each stands in the armpit of a small, short, tubular, triangular bract and has a two-keeled bracteole. The lower part of the cup is tubular, striped, and ends in three triangular lobes. The crown is divided into three triangular valvate lobes almost to the base . The six stamens are at the base of the corolla lobes, their filaments are fleshy, long and curved inwards at the tip. The anthers are oblong, medifix, arrow-shaped at the base, and latrors. The rudiment of the stamp is small. The pollen is bisymmetrical and monoporous, with the germ opening on one of the two short axes of the pollen grain.
The female flowers are in dyads, each supported by a small, triangular bract. The dyad consists of a female and a sterile male flower as well as two double-sided, cup-shaped bracteoles. The sterile male flower is often twisted and has empty, flat anthers. The female flowers are larger than the male. The calyx is cup-shaped, striped, the lobes triangular and valvate. The crown tears almost to the base into three triangular, valvate lobes. The six staminodes are epipetal. The gynoeceum is incompletely triple with one ovule per fruit compartment. It is egg-shaped and scaly with three scars .
Fruits and seeds
The fruit is solitary, spherical or egg-shaped and beaked. At the top are scar remains. The exocarp is covered with vertical rows of downward-facing, magenta to chestnut-colored scales. The mesocarp becomes thin and dry when the fruit is ripe, an endocarp is not differentiated. The seed starts at the base, its sarcotesta is thick and sweet-tasting. The endosperm is homogeneous, the embryo is basal.
Distribution and locations
One species occurs on the Malay Peninsula and Borneo , the other two only on Borneo. On Borneo, all three species occur in small populations on podsolized soils on ridges at around 700 to 1000 m above sea level. This is the transition area between lowland and mountain rainforest. They are also found in the Kerangas , the heather forests. On the Malay Peninsula, Pogonotium ursinum grows in dipterocarp forests.
Systematics
The genus Pogonotium J. Dransf. is placed within the family Arecaceae in the subfamily Calamoideae , Tribus Calameae and Subtribus Calaminae . Within the subtribe it forms a clade with Ceratolobus and Daemonorops . The monophyly of the genus has not yet been investigated (as of 2008).
Today the species of this genus are often placed in the genus Calamus . The following species are named for this genus:
- Pogonotium divaricatum J. Transf. : The home is Sarawak on Borneo.
- Pogonotium moorei J. Transf. : The home is Sarawak on Borneo.
- Pogonotium ursinum (Becc.) J.Dransf. : The home is Malaysia and Borneo.
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. 206-207.
Individual evidence
- ↑ Rafaël Govaerts (Ed.): Pogonotium. In: World Checklist of Selected Plant Families (WCSP) - The Board of Trustees of the Royal Botanic Gardens, Kew . Retrieved April 15, 2020.
Web links
- Pogonotium on the homepage of the Fairchild Tropical Botanic Garden