Sommieria leucophylla
| Sommieria leucophylla | ||||||||||||
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Sommieria leucophylla |
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| Systematics | ||||||||||||
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| Scientific name of the genus | ||||||||||||
| Sommieria | ||||||||||||
| Becc. | ||||||||||||
| Scientific name of the species | ||||||||||||
| Sommieria leucophylla | ||||||||||||
| Becc. |
Sommieria leucophylla is only Guinea occurring plant species from the family of the palm family (Arecaceae). It is the only species in the genus Sommieria . This palm is very small and has little or no leaves that are dark green on the top and hairy white on the underside. The inflorescence has a long stem and is not branched, the fruits are small and have cork warts . The species grows in the undergrowth of forests, its leaves are used to cover roofs.
features
Sommieria leucophylla has delicate, cylindrical trunks 3 to 4 cm in diameter. The trunk grows to a maximum of three meters high, but it can also be missing. It looks like that of a small coconut palm . The trunk surface is light brown to gray and closely covered with ring-shaped leaf scars . In the cross-section, a thin outer bark less than 1 mm thick can be seen. Inwardly, there is an inner bark with evenly distributed vascular bundles . Starch is stored in the inner bark . The wood is soft, there are no black fibers as in the closely related species.
leaves
The crown consists of up to 40 leaves . Especially with plants that grow in deep shade, many dead leaves remain on the plant. The leaves grow for a long time and remain on the plant for a long time, but exact data are not known. The crown acts as a trap for litter, in which micro and macro destructors such as fungi, arthropods and earthworms live and break down the litter. When it rains, the nutrients are washed into the soil at the roots of the palm.
The leaves are 92 to 180 cm long and 12 to 30 cm wide. They are whole and divided into two parts. The two halves of the leaf are usually not divided. More rarely, the upper part of the leaf is divided into two and at the lower end of the leaf there are one or two pairs of narrow, pointed segments. The ends of the leaves are pointed to rounded, with the apical edge double-serrated. Leaf shape, segmentation and perforation are quite variable. The upper side of the leaf is usually dark green, with a range from light to dark green. The underside is white, cream-colored or light brown. The petiole is 10 to 38.5 cm long, the rachis 40 to 115 cm.
Hairiness
The leaves and inflorescences are hairy. There are two types of hair: woolly hair and white, amorphous hair. The woolly hair is cream-colored to dark brown and is found on inflorescences, petioles, leaf sheaths and, rarely, on the underside of the leaf hachis. The white, amorphous hairs can be found on the underside of the leaf and are always present. It appears waxy, but does not melt when heated. Hairiness varies widely within and between individuals in a population, and also changes with age, decreasing with age.
inflorescence
The inflorescence stands between the leaves and is single. At flowering time it is up to 160 cm long. It branches once, rarely twice. In the young bud, the inflorescence is surrounded by a cream-colored to light brown cover leaf . There is a paper-like cover sheet on the peduncle that is at the tip of the stem or a few inches below it. These two bracts tear lengthways when the peduncle and its side branches stretch as they grow. At this point the flowers are only partially developed. The inflorescence stalk is up to 136 cm long.
The inflorescence axis is very short. The side branches protrude from the tip of the peduncle. They are screwy, round in cross-section, the lowest are sometimes branched. The bracts of the lateral axes are triangular to kidney-shaped. Three of the flowers stand in small pits along the lateral axis.
The inflorescence appears from the bracts three to six months before the anthesis . The inflorescences are pronounced proterandric , so self-pollination within an inflorescence is not possible. The pollinators are unknown, ants have been observed as flower visitors, and small insect larvae can often be observed in the female flowers.
blossoms
The three groups of flowers consist of a central female and two lateral male flowers. The male flowers are cream-colored to light brown in the bud stage and white to cream-colored when they flower. They are smaller than the female flowers. The female flowers are initially not visible, but rather hidden by the male. Only after the male flowers have fallen off do the female ones become visible and grow.
The male flowers are around 2.5 mm in diameter. They have three free sepals that are arranged like roof tiles . The sepals are semicircular to kidney-shaped and cream-colored to light brown. There may be thin brown hair on the outside. They are heavily keeled and sometimes have two or three lobes on top. The three petals are free, egg-shaped to triangular and cream-colored to brown. The six stamens are arranged in a whorl, the anthers are bent inward in the bud, sometimes also twisted. The ovary rudiment is columnar and shorter than the stamens.
The female flowers also have three sepals and three petals each. Their diameter is 2.5 to 3 mm. The petals are free or briefly fused at the base. They are rounded triangular and cream-colored to light brown. They have two to six tooth-like staminodes . The gynoeceum is egg-shaped, a stylus is not recognizable. There are three apical scars . The flowers are not fragrant.
Fruits and seeds
The fruits are small, round and contain a seed . They are 9 to 15 × 8 to 15 mm in size. The petals are retained on the fruit, as are the scars. The exocarp is initially smooth, soon after fertilization it dries up and dies. It will turn dark brown and tear as the fruit grows. The mesocarp is spongy and fleshy and covered with pyramidal to hexagonal cork warts when the fruit ripens , these are usually bright pink. The pericarp contains tannin-containing cells, vascular bundles with scattered fiber sheaths and brachysclereids .
The seeds are spherical, egg-shaped or ellipsoidal. They have a flat raphe that runs from the navel to the tip of the seed. The navel is narrow and is located at the base of the seed. The endosperm is homogeneous, the embryo sits subbasally. The seeds germinate after three to twelve months.
Distribution and ecology
Sommieria leucophylla is endemic to New Guinea . It occurs only on the western half of the island, which belongs to Indonesia, and on Waigeo as the only offshore island. The known sites are mainly on the Vogelkopf Peninsula, the northernmost finds come from Mamberamo , the southernmost from Timika . Only the easternmost sites are just on Papua New Guinean territory. This scattered distribution can either be due to unequal collection or an unknown link between the species and specific location conditions.
Most known individuals grow on slopes or on the valley floor. They grow mostly on Podzol or alluvial soils at 5 to 500 m above sea level . The pH is between 3.5 and 6.2. The temperature range is between 22 and 28 ° C. The plants grow in 40 to 85% shaded areas, so they are plants of the forest undergrowth.
The mechanisms of propagation are unknown. Based on the color of the fruits, animal spread is to be expected, and spread over short distances by gravity is also discussed.
Systematics
Sommieria was traditionally placed in the Subtribus Iguarininae of the Areceae tribe , but in the work of John Dransfield and colleagues in 2005, it was transferred to the new Pelagodoxeae tribe together with Pelagodoxa .
The first person to describe the genus and the species is Odoardo Beccari , who described Sommieria leucophylla in 1877. The generic name honors the Italian botanist Carlo Pietro Stefano Sommier (1848–1922). Until 1915 he described two more species of the genus, Sommieria elegans and Sommieria affinis . Heatubun (2002) showed in a processing of all known herbarium specimens that the separation of the genus into three species cannot be maintained, since all traits traditionally used for differentiation show continuous transitions.
use
Like other palm species that grow in the undergrowth of the forests, Sommieria has little economic importance. The leaves are traditionally used for roofing. The Arfak in the Manokwari area often used the leaves for this as well as for wrapping food. Some palm populations are therefore practically completely defoliated.
The species is endangered by the conversion of their locations into oil palm plantations .
supporting documents
literature
- Charlie D. Heatubun: A monograph of Sommieria (Arecaceae) . In: Kew Bulletin. Volume 57, 2002, pp. 599-611.
Individual evidence
- ^ 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)
- ^ Robert Lee Riffle, Paul Craft: An Encyclopedia of Cultivated Palms. 4th edition. Timber Press, Portland 2007, ISBN 978-0-88192-558-6 , p. 454.
