Rhopaloblasts

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Rhopaloblasts
Systematics
Class : Bedecktsamer (Magnoliopsida)
Monocots
Commelinids
Order : Palm- like arecales
Family : Palm family (Arecaceae)
Genre : Rhopaloblasts
Scientific name
Rhopaloblasts
Scheff.

Rhopaloblaste is a genus within the family palmaceae (Arecaceae). They grow in tropical lowland rainforests as undergrowth or in the middle layer, less often in the upper tree layer.

description

Vegetative characteristics

The Rhopaloblast species are medium-sized, single-stemmed palms with heights of 15 to 20 meters. Only Rhopaloplaste singaporensis is slender, multi-stemmed and less than 5 meters tall. The base of the trunk is often thickened. All representatives are unarmed and monocial . Depending on the species, the trunk is slim (2 to 4 cm in diameter) or thick (up to 35, rarely 40 cm). The leaf scars form clear and noticeable rings. The outer part of the trunk is black and very hard, the inner part is soft with few fibers.

The crown consists of 5 to 17 leaves . The long, tubular leaf sheaths form a clear corolla at the end of the stem. The rachis and the base of the leaflets are covered with brown-black, membranous scales on the upper side. The upper side of the leaflets is dark green and shiny, the underside dull or pale green. Even the first leaf of the seedling ( eophyll ) is finely pinnate.

Leaf sheath, leaves and inflorescence are clearly hairy, with different hair types. Dense, brown to gray-brown, overlapping scales are found on the leaf sheaths; pressed, membranous scales on petiole; twisted, brown-black, membranous scales on the rachis, which are particularly close at the base of the pinna; and reddish brown to grayish brown scales along the underside of the midribs of the leaflets. The hair on the inflorescence is thinner, on the young side arms there are irregular scales and sometimes star hairs.

Generative characteristics

The inflorescence stands between the leaves and is branched one to four times, rarely five times. The two lower branches are strongly bent back, with the exception of Rhopaloblasts singaporensis . Here the inflorescence is reduced. In the bud stage the inflorescence Saxony and viscera are in Vorblatt and bract rolled. The inflorescence stalk is short, the inflorescence axis between 35 and 100 cm long. It has numerous side axes.

The flowers stand along the side axes in triads with a central female and two lateral male flowers. The males are slightly longer than the females. Each triad stands in the armpits of a lip-shaped bract , only in Rhopaloblast ceramica they stand in small pits. Both male and female flowers have three short, strongly overlapping, rounded sepals . The petals of the female flowers are similar to the sepals, those of the male are longer and flap-shaped . The male flowers have six stamens that are bent inwards in the bud. Their stamens are fused at the base, the ovary -Rudiment is conical almost as long as the stamens. In the female flower there are four staminodes , which are irregularly fused to form a lobed ring. The ovary is irregularly ovoid, has a seed compartment (is unilocular), a stylus is missing, but there are three conspicuous, apical scars .

The shape and size of the fruits are important features for differentiating the individual species. They are usually symmetrical, only slightly asymmetrical in Rhopaloblasts ceramica . The shape ranges from egg-shaped to ellipsoidal to spherical. They are 10 to 35 mm long and 8 to 16 mm wide. When immature, they are green; when ripe they turn orange-yellow to red. The scars remain apically on the fruit, the perianth also remains on the fruit, in different sizes. The exocarp is smooth, the mesocarp contains no fiber scleraids or tannin cells, instead flat longitudinal fibers in one or more layers on the edge of the yellow endocarp .

The shape of the seeds is similar to that of the fruit. The seeds are brown to black, the hilum is slightly to heavily indented on the adaxial side. The endosperm is deeply furrowed, the embryo is basal and club-shaped.

Occurrence

The genus Rhopaloblasts occurs in Southeast Asia and has a very disjoint area . In the westernmost area there is one species on the Nicobar Islands , another on the Malay Peninsula and Singapore . To the east it is absent on Sumatra , Java , Borneo , Sulawesi , the Lesser Sunda Islands and the Philippines . Two species occur in the Moluccas and New Guinea , with no occurrences in the eastern part of New Guinea. One species each occurs in New Ireland and the Solomon Islands .

The rhopaloblast species thrive in the tropical rainforest at altitudes of up to 900 meters. They usually grow in lowland rainforests and in lower mountain forests, but are absent in middle and higher mountain regions. They easily establish themselves in secondary forests and abandoned gardens.

Systematics

The genus Rhopaloblasts was established in 1876 by Rudolph Herman Christiaan Carel Scheffer . A synonym for rhopaloblasts Scheff. is Ptychoraphis Becc. The genus Rhopaloblasts Scheff. is placed within the family Araceae in the subfamily Arecoideae , tribe Areceae , but not assigned to any subtribe here.

Roy Banka and William J. Baker accepted six species in their 2004 generic revision :

supporting documents

  • Roy Banka, William J. Baker: A monograph of the genus Rhopaloblasts (Arecaceae). In: Kew Bulletin , Volume 59, 2004, pp. 47-60.

Individual evidence

  1. ↑ a b Rafaël Govaerts (Ed.): Rhopaloblasts. In: World Checklist of Selected Plant Families (WCSP) - The Board of Trustees of the Royal Botanic Gardens, Kew . Retrieved December 1, 2014.
  2. ^ John Dransfield, Natalie W. Uhl, Conny B. Asmussen, William J. Baker, Madeline M. Harley, Carl E. Lewis: A New Phylogenetic Classification of the Palm Family, Arecaceae. In: Kew Bulletin , Volume 60, 2005, pp. 559-569. JSTOR 25070242
  3. ^ Roy Banka, William J. Baker: A monograph of the genus Rhopaloblasts (Arecaceae). In: Kew Bulletin , Volume 59, 2004, pp. 47-60.