Potoxylon
Encyclopedia
Potoxylon is a genus of evergreen
trees belonging to the Laurel family, Lauraceae
. Its only species
: Potoxylon melagangai (Symington
) Kostermans
, is native to Borneo
in tropical Asia
. The genus was described by André Joseph Guillaume Henri Kostermans
in 1978.
They are widespread in across Borneo island. Potoxylon is an evergreen hermaphrodite tree with gray bark. Leaves are alternate, simple and entire leathery, pinnatinervian. The flowers are bisexual and actinomorphic with six tepals biseriate, 9 stamens triseriate, the ovary superior and unilocular, grouped in axillary spikes. Berry-like drupes, ellipsoid. The fruit, a berry
has a single seed dispersed by birds.
in tropical mountain cloud forest
s, and like most of their counterparts laurifolia in the world, they are vigorous species with a great ability to populate the habitat that is conducive. The natural habitat is rainforest which is cloud-covered for much of the year. The species is found in forests that face threats of destruction by human deforestation
.
Because of the special lack of worldwide knowledge about the family lauraceae
in general, very little is known about their diversity. The knowledge of this family on a national level is that to be expected in countries with limited economic means, i.e. the vast majority of species is indeterminate or at least poorly determined. On the other hand, a high percentage of recently described new species come from collections made in these countries. Therefore an increase in the study of the family on national level is of utmost importance for the progress of the systematics
of the family in general. Recent monographs of the small and medium genera of lauraceae with up to 100 species per genus have produced a high increase in the number of known species. This high increase is expected for other genera as well, particularly for those with more than 150 species recorded, bringing an expected considerable increase in the total number of species of the family.
A related vegetal community evolved millions of years ago on the supercontinent of Gondwana
, and species of this community are now found on several separate areas of the Southern Hemisphere
, including South America
, Africa
, New Zealand
, Australia
and New Caledonia
.
The endemic genus of Borneo currently includes A single species and is threatened by habitat loss. Exploitation of the natural populations is in detriment of the rainforest.
Potoxylon is found inhabiting wet lands in tropical montane forests
. The islander Potoxylon species can not endure the continental winter outside its natural habitat and could be killed by cold weather.
Evergreen
In botany, an evergreen plant is a plant that has leaves in all seasons. This contrasts with deciduous plants, which completely lose their foliage during the winter or dry season.There are many different kinds of evergreen plants, both trees and shrubs...
trees belonging to the Laurel family, Lauraceae
Lauraceae
The Lauraceae or Laurel family comprises a group of flowering plants included in the order Laurales. The family contains about 55 genera and over 3500, perhaps as many as 4000, species world-wide, mostly from warm or tropical regions, especially Southeast Asia and South America...
. Its only species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
: Potoxylon melagangai (Symington
Symington
-People:*J. Fife Symington Jr. , American diplomat*Fife Symington III , American politician; Governor of Arizona*Gaye Symington , American politician, Speaker of the Vermont House of Representatives...
) Kostermans
André Joseph Guillaume Henri Kostermans
Dr. André Joseph Guillaume Henri 'Doc' Kostermans was a botanist. He was born in Purworejo, Java, Dutch East Indies, and educated at Utrecht University, taking his doctoral degree in 1936 with a paper on Surinamese Lauraceae.He spent most of his professional life studying the plants of...
, is native to Borneo
Borneo
Borneo is the third largest island in the world and is located north of Java Island, Indonesia, at the geographic centre of Maritime Southeast Asia....
in tropical Asia
Asia
Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...
. The genus was described by André Joseph Guillaume Henri Kostermans
André Joseph Guillaume Henri Kostermans
Dr. André Joseph Guillaume Henri 'Doc' Kostermans was a botanist. He was born in Purworejo, Java, Dutch East Indies, and educated at Utrecht University, taking his doctoral degree in 1936 with a paper on Surinamese Lauraceae.He spent most of his professional life studying the plants of...
in 1978.
Overview
The genus is characterized by an extremely rare combination of characters that have occurred in the species in its own distinct genus. There is little information regarding the species due to its scarcity and the remoteness of their populations.They are widespread in across Borneo island. Potoxylon is an evergreen hermaphrodite tree with gray bark. Leaves are alternate, simple and entire leathery, pinnatinervian. The flowers are bisexual and actinomorphic with six tepals biseriate, 9 stamens triseriate, the ovary superior and unilocular, grouped in axillary spikes. Berry-like drupes, ellipsoid. The fruit, a berry
Berry
The botanical definition of a berry is a fleshy fruit produced from a single ovary. Grapes are an example. The berry is the most common type of fleshy fruit in which the entire ovary wall ripens into an edible pericarp. They may have one or more carpels with a thin covering and fleshy interiors....
has a single seed dispersed by birds.
Ecology
The ecological requirements of the genus are those of the laurel forestLaurel forest
Laurel forest is a subtropical or mild temperate forest, found in areas with high humidity and relatively stable and mild temperatures. They are characterized by tree species with evergreen, glossy, enlongated leaves, known as laurophyll or lauroide...
in tropical mountain cloud forest
Cloud forest
A cloud forest, also called a fog forest, is a generally tropical or subtropical evergreen montane moist forest characterized by a persistent, frequent or seasonal low-level cloud cover, usually at the canopy level. Cloud forests often exhibit an abundance of mosses covering the ground and...
s, and like most of their counterparts laurifolia in the world, they are vigorous species with a great ability to populate the habitat that is conducive. The natural habitat is rainforest which is cloud-covered for much of the year. The species is found in forests that face threats of destruction by human deforestation
Deforestation
Deforestation is the removal of a forest or stand of trees where the land is thereafter converted to a nonforest use. Examples of deforestation include conversion of forestland to farms, ranches, or urban use....
.
Because of the special lack of worldwide knowledge about the family lauraceae
Lauraceae
The Lauraceae or Laurel family comprises a group of flowering plants included in the order Laurales. The family contains about 55 genera and over 3500, perhaps as many as 4000, species world-wide, mostly from warm or tropical regions, especially Southeast Asia and South America...
in general, very little is known about their diversity. The knowledge of this family on a national level is that to be expected in countries with limited economic means, i.e. the vast majority of species is indeterminate or at least poorly determined. On the other hand, a high percentage of recently described new species come from collections made in these countries. Therefore an increase in the study of the family on national level is of utmost importance for the progress of the systematics
Taxonomy
Taxonomy is the science of identifying and naming species, and arranging them into a classification. The field of taxonomy, sometimes referred to as "biological taxonomy", revolves around the description and use of taxonomic units, known as taxa...
of the family in general. Recent monographs of the small and medium genera of lauraceae with up to 100 species per genus have produced a high increase in the number of known species. This high increase is expected for other genera as well, particularly for those with more than 150 species recorded, bringing an expected considerable increase in the total number of species of the family.
A related vegetal community evolved millions of years ago on the supercontinent of Gondwana
Gondwana
In paleogeography, Gondwana , originally Gondwanaland, was the southernmost of two supercontinents that later became parts of the Pangaea supercontinent. It existed from approximately 510 to 180 million years ago . Gondwana is believed to have sutured between ca. 570 and 510 Mya,...
, and species of this community are now found on several separate areas of the Southern Hemisphere
Southern Hemisphere
The Southern Hemisphere is the part of Earth that lies south of the equator. The word hemisphere literally means 'half ball' or "half sphere"...
, including South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
, Africa
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
, New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...
, Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
and New Caledonia
New Caledonia
New Caledonia is a special collectivity of France located in the southwest Pacific Ocean, east of Australia and about from Metropolitan France. The archipelago, part of the Melanesia subregion, includes the main island of Grande Terre, the Loyalty Islands, the Belep archipelago, the Isle of...
.
The endemic genus of Borneo currently includes A single species and is threatened by habitat loss. Exploitation of the natural populations is in detriment of the rainforest.
Potoxylon is found inhabiting wet lands in tropical montane forests
Cloud forest
A cloud forest, also called a fog forest, is a generally tropical or subtropical evergreen montane moist forest characterized by a persistent, frequent or seasonal low-level cloud cover, usually at the canopy level. Cloud forests often exhibit an abundance of mosses covering the ground and...
. The islander Potoxylon species can not endure the continental winter outside its natural habitat and could be killed by cold weather.