Roscheria melanochaetes

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Roscheria melanochaetes
Roscheria melanochaetes - Victoria 1.jpg

Roscheria melanochaetes

Systematics
Monocots
Commelinids
Order : Palm- like arecales
Family : Palm family (Arecaceae)
Genre : Roscheria
Type : Roscheria melanochaetes
Scientific name of the  genus
Roscheria
H. Wendl. ex Balf.f.
Scientific name of the  species
Roscheria melanochaetes
( H.Wendl. ) H.Wendl. ex Balf.f.

Roscheria melanochaetes is a species of palm endemic to the Seychelles . It is the only species in the genus Roscheria .

features

Roscheria melanochaetes is a small to medium-sized, single-stemmed palm. Young plants are thorny , older ones hardly reinforced. They are single sexed ( monoecious ) and flowering several times. The trunk is erect, glabrous and covered with conspicuous, ring-shaped leaf scars. On the youthful leaf scars there are rings of black thorns, later they are unarmed or have a few weak thorns. Air roots sometimes grow at the base of the trunk .

The chromosome number is 2n = 32.

leaves

The leaves are pinnate irregularly. The leaf sheaths are Roehrig and form a clearly pronounced crown shaft. They are covered with brown scales and armed with scattered, short, black thorns. The thorns are closest to the base of the petiole. The petiole is deeply furrowed on the top and rounded on the underside. At the base it is densely reinforced with short, black, easy-to-strip thorns. The rachis is unarmed. The leaf blade in young palms is completely or in two parts, in older palms it is irregularly divided into leaflets that are folded one or more times. Leaflets with one rib are pointed, those with several are blunt or frayed. The upper side of the leaf is bare, the underside with numerous tiny, point-shaped scales and conspicuous hairs along the central ribs.

Inflorescences

The inflorescences are single. At first they are between the leaves (interfoliar), after the leaf fall they are then under the leaf crown (infrafoliar). The inflorescence is strongly branched in three, rarely in the lower area up to four orders. The inflorescence stalk is long, crescent-shaped in cross section and winged at the base. The cover sheet starts a little away from the base of the stem. It is membranous to leathery, tubed, persistent, flattened and two-keeled. At the top it is briefly divided. It is unarmed and scattered with small scales. The bract on the peduncle stands a little away from the cover sheet and is usually significantly longer than this. It is initially piping, then tears open over most of its length and finally falls off.

The inflorescence axis is significantly shorter than the stem. Their bracts are small, triangular and inconspicuous. The side axes of all orders are free of side axes and flowers in the lower part over a short to longer distance. All axes are covered with scales. The first-order lateral axes are almost in two rows (subdistich), the proximal ones are longer than the distal ones. The flower-bearing axes (rachillae) are slender, rather short and flexible. They have small bracts in a spiral arrangement, in the axils of which there are flower triads in the middle rachilla area, then distally paired and solitary flowers.

blossoms

The male flowers are very small and spherical in the bud stage. The three sepals are largely free, imbricat , broad, triangular and keeled. The three petals are free, valvate and more than twice as long as the calyx. They are also wide and triangular. The six stamens have fused stamens at the base. The free section is short, wide, triangular. The anthers are round and small. The rudiment of punches is relatively large.

The female flowers are larger than the male. The three sepals are free, thick, imbricat, broad and round. The three petals are free, broad, triangular, the tips briefly valvate, otherwise imbricat. The six staminodes are tooth-shaped and fused in the lower area. The gynoeceum is asymmetrically egg-shaped and has a fruit compartment and an ovule . The scar is apical and has three lobes. The ovule starts laterally.

fruit

The fruit is small, spherical or ellipsoidal. When ripe it is red. The inflorescence remains at maturity, the scar remains are subbasal. The exocarp is smooth, the mesocarp very thin and provided with a layer of anastomosing fibers and numerous raphids . The endocarp is relatively thick, leg-like, smooth and with a basal germ opening (operculum). The seed is basal and has a rounded umbilicus (hilum). The raphe is hardly branched and anastomosing. The endosperm is deeply furrowed (ruminate).

Distribution and locations

The distribution area of Roscheria melanochaetes is limited to the Seychelles islands Mahé and Silhouette . They are part of the undergrowth of mountain rainforests and are very rarely found below 500 m above sea level. At about 750 m above sea level, the species can form pure stands on steep slopes in the undergrowth of Northia forests.

Systematics

The genus Roscheria is placed within the family Arecaceae in the subfamily Arecoideae , Tribus Areceae and Subtribus Verschaffeltiinae . Its sister genus is Verschaffeltia .

In the World Checklist of Selected Plant Families of the Royal Botanic Gardens, Kew , only the species Roscheria melanochaetes is recognized.

The genus is named after Albrecht Roscher (1836–1860), a German East Africa researcher.

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. 615-618.

Individual evidence

  1. ↑ Rafaël Govaerts (ed.): Roscheria. In: World Checklist of Selected Plant Families (WCSP) - The Board of Trustees of the Royal Botanic Gardens, Kew . Retrieved June 3, 2010.

Web links