Sclerosperm
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| Scientific name | ||||||||||||
| Sclerosperm | ||||||||||||
| G. Mann & H. Wendl. |
Sclerosperma is a genus of palm that is native to the rainforests of West Africa. It is the only representative of the Sclerospermeae tribe . The representatives have an unusual inflorescence for palm trees: it is erect, unbranched and has crowded flowers.
features
The representatives are mostly stemless and grow in clumps. They often form thickets. They are unarmed, monoecious and blooming several times. The trunk is, if present, creeping or upright, rather stocky and densely covered with ring-shaped leaf scars.
The number of chromosomes is unknown.
leaves
The leaves are reduplicate (cross section of the leaflets Λ-shaped), two-part (bifid) or pinnate, and very large. The leaves of young plants are deeply bifid. The leaf sheath is rather short and tears open opposite the petiole , the edges are fibrous. The petiole is long, slender, furrowed on the top, rounded on the underside. The leaflets , if any, consist of several very narrow folds. The central ribs are clearly developed. The leaf blade is dark on the upper side, dense amorphous white hairs on the underside and small scales on the nerves. The leaflets are torn out at the end (premors). The leaf margin is finely serrated.
Inflorescences
The inflorescences are between the leaves (interfoliar) and are hidden between the leaf bases, sometimes also covered by deposits. They are erect, stocky and spike-shaped. The peduncle is very short, elliptical in cross section and densely hairy. The cover sheet is rather short, strongly two-keeled and later frayed. The bract on the peduncle is longer than the cover sheet, tubular and forms a dense network of fibers around the flowers. It opens distally, partially exposing the inflorescence. Two more, incomplete, pointed bracts stand laterally directly below the flowers. The inflorescence axis is longer than the inflorescence stalk, but still short, stocky and bears a few (around 12) flower triads at the base and numerous rows of male flowers distally. Each triad is carried by a flat, pointed, fibrous bract, the male by small, pointed bracts. The flower bracts are present in the triads and are flat, rounded and partially fused.
blossoms
The male flowers of the triads are stalked and asymmetrical, the distal flowers are sessile and symmetrical. All male flowers have three free sepals , the basal imbricat stand. They are long, narrowed towards the top, truncated apically or with a short central point. The three petals are free, valvat with flattened tips. There are 60 to 100 stamens . Their filaments are very short, rather triangular, the anthers are elongated, basifix, open latrörs. The connective is clearly developed. One stamp rudiment is missing. The pollen is symmetrical and in polar view it is flattened triangular. It is heteropolar: on the distal side there are three operculate germ pores subapically.
The female flowers are larger than the male and broadly ovate. The three sepals are fused into a three-lobed, bare cup, or the edges of two sepals are free and imbricat. The three petals are asymmetrical, pulpy imbricat with thick valvate tips. There are six very small staminodes , but they can also be absent. The gynoeceum is egg-shaped, single-fan with an ovule and covered with thin, brown scales. The scar is large, cap-shaped and triangular. The ovule is more or less drooping and probably campylotropic.
Fruits and seeds
The fruits are spherical to obovate. Apically, they are slightly indented around the short beak with the remains of the scar. The color at fruit ripeness is purple to black. The exocarp is thin, the mesocarp is thin, parenchymal with (possibly) silicate inclusions. The endocarp is bony, thick and irregularly provided with shallow pits on the outside. The seed is spherical to obovate, somewhat rough. The hilum is elongated, the endosperm is homogeneous, the embryo is basal.
Distribution and locations
The genus occurs in the perhumid tropical rainforests of equatorial West Africa, in the area around the Gulf of Guinea. The representatives grow mainly in low-lying, moist, swampy areas.
Systematics
The genus Sclerosperma G. Mann & H. Wendl. is placed within the Arecaceae family in the Arecoideae subfamily and alone forms the Sclerospermeae tribe. The monophyly was not investigated. The Sclerospermeae together with the Oranieae and the Podococceae form a clade .
The Royal Botanic Gardens, Kew's World Checklist of Selected Plant Families recognizes the following species:
- Sclerosperma mannii H. Wendl. : The range extends from Liberia and Nigeria to northeastern Angola.
- Sclerosperma profizianum Valk. & Sunderl. : The distribution area of this species, which was only newly described in 2008, extends from Ghana to northeastern Angola.
- Sclerosperma walkeri A. Chev. : The homeland is Gabon and western Zaire.
Sclerosperma was first described by G. Mann and Hermann Wendland in 1864 , the type species is Sclerosperma mannii . The generic name is derived from the ancient Greek words for hard and seeds, a reference to the hard endosperm.
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. 389-391.
Individual evidence
- ↑ Rafaël Govaerts (Ed.): Sclerosperma. In: World Checklist of Selected Plant Families (WCSP) - The Board of Trustees of the Royal Botanic Gardens, Kew . Retrieved March 11, 2012.