Podococcus
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| G. Mann & H. Wendl. |
Podococcus is a genus of palm native to the rainforests of West Africa. It is the only representative of the Podococceae tribe .
features
The representatives are slender, upright, unreinforced palms with pinnate leaves. They grow in groups. They are monoecious and bloom several times. The trunk is erect, slender, reed-like, or it is underground. It is covered with reddish-brown, fibrous leaf bases, later also free of these and provided with rings of leaf scars. At the base of the trunk there are axillary stolons that spread horizontally, eventually grow upright, develop roots and thus form new shoots. Roots with pneumatophores are also formed.
The number of chromosomes is unknown.
leaves
A palm has few pinnate leaves . The first leaves on new shoots are undivided, elliptical, with pinnate ribs, a serrated edge and a slightly two-part (bifidem) end. The leaf sheath is tubular and tears opposite the petiole with fibrous edges. The petiole is very slender, slightly furrowed on the top, rounded on the underside, covered with punctiform scales and sloping hairs. The rachis resembles the petiole, but is longer, becomes thinner towards the end and also extends through the terminal, often bifid terminal leaflet.
The leaflets are rhombic and simply folded. The lower half of each leaflet is wedge-shaped with a smooth edge, the upper half is triangular with a double-serrated edge. Five large leaf veins extend from the base of the leaflet, a central rib is not formed. The leaf blade is bare on the upper side, on the underside there are slender, tannic hairs with a thickened base.
Inflorescences
The inflorescences stand individually between the leaves (interfoliar). They are spike-shaped , initially upright, hanging when the fruit is ripe. They are proterandrian . The peduncle is very slender and has sloping hair. The cover sheet sits basal and is tubular, two-keeled and disintegrates into long fibers. There are two to three bracts on the peduncle, which start at large intervals above the cover sheet. They are Roehrig and fall apart like the cover sheet. The inflorescence axis is about the same length or longer than the stem and bears flower triads in a spiral arrangement, paired or single male flowers in the distal area. The flowers are in pits. The bracts, which are the bracts of the triads, are only present as slightly raised lower edges of the pits. The bracts of the flowers are membranous, irregular and mostly pointed.
blossoms
The male flowers are mostly adaxial to the female. The three sepals are free, slightly keeled, their tips are irregular or rounded, their base is imbricat . The three petals are valvate and about twice as long as the sepals. For flowering, they are connected to about two-thirds of their length to form a firm receptacle that is about as long as the flower pit. The free corolla lobes protrude into the open and are spread. The six stamens are in two circles, the outer opposite the sepals and shorter than the inner antepetal stamens. The filaments are awl-shaped, rather short and curved inward. The anther are short, dorsifix near the base, and open to latrors. The connective are rich in tannins . The rudiment of the stamp is short and three-lobed. The pollen is ellipsoidal with slight to marked asymmetry. The germ opening is a distal sulcus. The longest axis measures 27 to 32 microns.
The female flowers are symmetrical. The three sepals are free and irregular, and about half as long as the petals. The petals are fused to one another in the lower third up to halfway and connected to a firm receptacle that is about as long as the flower pit. The ends of the petals are imbricat in the bud, spread out to flower. The six staminodes are very small. The gynoeceum is ovate, triple with three ovules or with two abortive compartments. A stylus is not designed. The three stigmas are short and curved back towards the flower. The ovules are pendulous.
Fruits and seeds
The fruits are long, ellipsoidal or with ellipsoidal lobes. They are often curved. Their color is bright orange. They contain one to three seeds. The scar remnants are central in three-seeded fruits and laterally in single- and two-seeded fruits. The base of the fruit has a short stalk, the lobes develop horizontally to the axis of the flower. The exocarp is thin, smooth and rather leathery, the mesocarp is gelatine-like and has an inner layer of fibers. The endocarp is crusty. The seed is ellipsoidal, sits basal, and has a basal hilum. Anastomose the ramifications of the raphe . The endosperm is homogeneous. The embryo starts laterally near the middle.
Distribution and locations
The two types of Podococcus occur in West Africa from Nigeria to Gabon , with the area ranging from the Niger Delta to almost the Congo River . They grow in the lowland rainforest and only occur up to 200 km from the coast. The spread largely overlaps with the spread of the Biafra Forest and closely related societies. The palm trees are missing in locations that were previously cultivated and also near roads. They mostly grow on ferrallitic Latosol soils, but are not limited to this type of soil.
Systematics
The genus Podococcus G. Mann & H. Wendl. is placed within the Arecaceae family in the Arecoideae subfamily and alone forms the Podococceae tribe. The monophyly was not investigated. The Podococceae form together with the Oranieae and the Sclerospermeae a clade .
The Royal Botanic Gardens, Kew's World Checklist of Selected Plant Families recognizes the following species:
- Podococcus acaulis Hua : The homeland is Gabon and the Republic of Congo .
- Podococcus barteri G. Mann & H. Wendl. : The distribution ranges from southern Nigeria to western and central tropical Africa.
Podococcus was first described by G. Mann and Hermann Wendland in 1864 , the type species is Podococcus barteri . The generic name is derived from the ancient Greek words for foot and seed or berry, a reference to the characteristic stalked fruits.
The Podococceae tribe was established in 1986 by John Dransfield and Natalie Uhl .
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. 383-386.
Individual evidence
- ↑ Rafaël Govaerts (ed.): Podococcus. In: World Checklist of Selected Plant Families (WCSP) - The Board of Trustees of the Royal Botanic Gardens, Kew . Retrieved February 26, 2012.