Pleurothyrium
Encyclopedia
Pleurothyrium is a genus of plant
Plant
Plants are living organisms belonging to the kingdom Plantae. Precise definitions of the kingdom vary, but as the term is used here, plants include familiar organisms such as trees, flowers, herbs, bushes, grasses, vines, ferns, mosses, and green algae. The group is also called green plants or...

 in 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...

. They are present in Laurel forest
Laurel 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...

 habitat and montane 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...

.

Overview

Pleurothyrium is a genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 of neotropical distribution occurring 40 species distributed from Guatemala
Guatemala
Guatemala is a country in Central America bordered by Mexico to the north and west, the Pacific Ocean to the southwest, Belize to the northeast, the Caribbean to the east, and Honduras and El Salvador to the southeast...

 to Bolivia
Bolivia
Bolivia officially known as Plurinational State of Bolivia , is a landlocked country in central South America. It is the poorest country in South America...

, in Panama, Guatemala, Salvador, Honduras, Nicaragua, Costa Rica, Colombia, Venezuela, Ecuador
Ecuador
Ecuador , officially the Republic of Ecuador is a representative democratic republic in South America, bordered by Colombia on the north, Peru on the east and south, and by the Pacific Ocean to the west. It is one of only two countries in South America, along with Chile, that do not have a border...

, Peru, Bolivia... and extending to southern Brazil
Brazil
Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...

, of evergreen tree
Tree
A tree is a perennial woody plant. It is most often defined as a woody plant that has many secondary branches supported clear of the ground on a single main stem or trunk with clear apical dominance. A minimum height specification at maturity is cited by some authors, varying from 3 m to...

s and bush
Bush
-Nouns:* Shrub, a type of woody plant, smaller than normal trees. Usually grows in the soil. Most bushes are low to the ground and have branches which rise up from the bottom of the plant....

es of the family of the Laurel in the great 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...

 family. Its natural habitat
Habitat
* Habitat , a place where a species lives and grows*Human habitat, a place where humans live, work or play** Space habitat, a space station intended as a permanent settlement...

 are subtropical or tropical moist montane
Montane
In biogeography, montane is the highland area located below the subalpine zone. Montane regions generally have cooler temperatures and often have higher rainfall than the adjacent lowland regions, and are frequently home to distinct communities of plants and animals.The term "montane" means "of the...

s where this genus have many Endemisms.
In Brazil is represented by 13 species, and the State of Rio de Janeiro, only for P. amplifolium (Mez) Rohwer (Werff 1993).

Description

They are monoecious tree
Tree
A tree is a perennial woody plant. It is most often defined as a woody plant that has many secondary branches supported clear of the ground on a single main stem or trunk with clear apical dominance. A minimum height specification at maturity is cited by some authors, varying from 3 m to...

s reaching up to 30 m high; Hermaphrodite
Hermaphrodite
In biology, a hermaphrodite is an organism that has reproductive organs normally associated with both male and female sexes.Many taxonomic groups of animals do not have separate sexes. In these groups, hermaphroditism is a normal condition, enabling a form of sexual reproduction in which both...

s. The leaves are alternate, without papillae on the abaxial epidermis, elliptical, with acute base and apex, chartaceous, glabrous or minutely puberulous on the back. The genus have small flowers. The inflorescence
Inflorescence
An inflorescence is a group or cluster of flowers arranged on a stem that is composed of a main branch or a complicated arrangement of branches. Strictly, it is the part of the shoot of seed plants where flowers are formed and which is accordingly modified...

s are paniculate, thyrsus-paniculate, cymose last branching, densely and shortly pubescent, flowers 7 mm in diameter, creamy white, fragrant. Flowers monoclinic with hypanthium urceolate, not compressed below the tepals, tepals 6, usually erect or reflexed, equal, inner surface with or without papillae. Androecium with 9 stamens fertile, fillets generally thinner than the anthers, anthers quadrilocelares: 1st and 2nd series with three stamens each, anthers with a pair of loculi with dehiscence side and a pair introrse, 3rd series with three stamens, a pair of glands in basis of fillets, well developed, sometimes fused, in some species, the stamens of the 3 series fuse into a mass like a pillow. Anthers with a pair of locelos extrorse and a couple side-extrorse; 4th grade estaminodial present, reduced with 3 staminodes, or absent. The fruit is a berry ellipsoid, partially surrounded by a top margin simple, tepals deciduous or persistent. 2 cm long and 1.5 cm wide when dry, ca 5 mm dome deep, with large lenticels. The berry have 1 seed dispersed frequently by birds.

Ecology

They have habitat preference by laurel forest
Laurel 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...

, and altitudinal range from low evergreen tropical forest in Amazon region but also in tropical mountain cloud forest. Species in less humid environment are smaller or less robust, with less abundant and thinner foliage and have oleifera cells that give trees a more fragrant aroma. Some species live in symbiosis with ants. Pleurothyrium is present in tropical and montane rainforest, in the Andean 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...

, but grow also in evergreen lowlands tropical laurel forests. Pleurothyrium mostly consist of trees, occurring at low elevations, but some species are living top at 1900 m.

The ecological requirements of the genus, are mostly those of fog moisture precipitating almost continuously in a natural habitat cloud-covered for much of the year. An ecosystem
Ecosystem
An ecosystem is a biological environment consisting of all the organisms living in a particular area, as well as all the nonliving , physical components of the environment with which the organisms interact, such as air, soil, water and sunlight....

 of great exuberance characterized by high humidity, no seasonal changes and with a wide variety of botanical and zoological species but also highly fragile against external aggressions.
The genus require continuously moist soil, and do not tolerate drought.
The most known trees are used by the timber industry. The fruit, a berry, is an important food source for birds. In some species the seed dispersal
Seed dispersal
Seed dispersal is the movement or transport of seeds away from the parent plant. Plants have limited mobility and consequently rely upon a variety of dispersal vectors to transport their propagules, including both abiotic and biotic vectors. Seeds can be dispersed away from the parent plant...

 is carried out by monkey
Monkey
A monkey is a primate, either an Old World monkey or a New World monkey. There are about 260 known living species of monkey. Many are arboreal, although there are species that live primarily on the ground, such as baboons. Monkeys are generally considered to be intelligent. Unlike apes, monkeys...

s, chipmunk
Chipmunk
Chipmunks are small striped squirrels native to North America and Asia. They are usually classed either as a single genus with three subgenera, or as three genera.-Etymology and taxonomy:...

s, or fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...

es.

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...

 was part 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,...

land flora and many genera also, migrated to South America via Antarctica in ocean landbridges by Paleocene time.
There they spread over most of the continent. When the north American and south American tectonic plates joined in late Neogene, volcanic mountain building created island chains which later formed the meso-American landbridge. Pliocene elevation created new habitats for speciation. While some genera died out in increasingly xerophytic Africa, starting with the freezing of Antarctica about 20 million years ago and the formation of the Benguela current, others, like Beilschmiedia
Beilschmiedia
Beilschmiedia is a genus of trees and shrubs in family Lauraceae. Most of its species grow in tropical climates, but a few of them are native to temperate regions, and they are widespread in tropical Asia, Africa, Madagascar, Australia, New Zealand, North America, Central America, the Caribbean,...

, and Nectandra
Nectandra
Nectandra is a genus of plant in family Lauraceae.-Overview:Plants from this genus have been used in the treatment of several clinical disorders in humans. It has been demonstrated that Nectandra plants have potential analgesic, antiinflammatory, febrifuge, energetic and hypotensive activities...

, which also reached south and meso-America, are still surviving today in Africa in a number of species. The genus Pleurothyrium is related with Nectandra, where the species were beforly classified. The genus Persea
Persea
Persea is a genus of about 150 species of evergreen trees belonging to the laurel family, Lauraceae. The best-known member of the genus is the avocado, P. americana, widely cultivated in subtropical regions for its large, edible fruit.-Overview:...

, however, died out in Africa, except for Persea indica
Persea indica
Persea indica is a species of plant in the Lauraceae family.It is found in the Azores, Madeira, and Canary Islands in Macaronesia. It is threatened by habitat loss.-Overview:...

, surviving in the fog shrouded mountains of the Canary Islands, which with Madagascar constitutes Africa's Laurel forest
Laurel 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...

 plant refugia. In meso-America, the genus Nectandra proliferated into new species and the berries of some of them constitute a valuable food supply for the quetzal
Quetzal
Quetzals are strikingly colored birds in the trogon family . They are found in forests and woodlands, especially in humid highlands, with the five species from the genus Pharomachrus being exclusively Neotropical, while the single Euptilotis species is almost entirely restricted to western Mexico...

, that lives in the montane rainforests of meso-America. Since this habitat is constantly threatened by encroching agriculture, the laurel forest animal or vegetal species had already become rare in many of its former habitats and are threatened by habitat loss.

The quetzal favorite fruits are berries of relatives of the avocado
Avocado
The avocado is a tree native to Central Mexico, classified in the flowering plant family Lauraceae along with cinnamon, camphor and bay laurel...

 family. Their differing maturing times in the 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...

 determine the migratory movements of the quetzals to differing elevation levels in the forests. With a gape width of 21 mm, the quetzal swallows the small berries (aquacatillos) whole, which he catches while flying through the lower canopy of the tree, and then regurgitates the seed within 100 meters from the tree. Wheelright in 1983 observed that parent quetzals take far less time intervals to deliver fruits to the young brood than insects or lizards, reflecting the ease of procuring fruits, as opposed to capturing animal prey. Since the young are fed exclusively berries in the first 2 weeks after hatching, these berries must be of high nutritional value. Usually only the total percentage of water, sugar, nitrogen, crude fats and carbohydrates are reported by ornithologists

Selected species

It contains the following species (but this list may be incomplete):
  • Pleurothyrium giganthum
    Pleurothyrium giganthum
    Pleurothyrium giganthum is a species of plant in the Lauraceae family. It is endemic to Ecuador. Its natural habitats are subtropical or tropical moist lowland forests and subtropical or tropical moist montanes.-Source:...

    , van der Werff
  • Pleurothyrium hexaglandulosum
    Pleurothyrium hexaglandulosum
    Pleurothyrium hexaglandulosum is a species of plant in the Lauraceae family. It is found in Costa Rica and Panama.-Source:* World Conservation Monitoring Centre 1998. . Downloaded on 23 August 2007....

    , van der Werff
  • Pleurothyrium obovatum
    Pleurothyrium obovatum
    Pleurothyrium obovatum is a species of plant in the Lauraceae family. It is endemic to Ecuador. Its natural habitat is subtropical or tropical moist montanes.-Source:* Muriel, P. & Pitman, N. 2004. . Downloaded on 23 August 2007....

    , van der Werff
  • Pleurothyrium roberto-andinoi
    Pleurothyrium roberto-andinoi
    Pleurothyrium roberto-andinoi is a species of plant in the Lauraceae family. It is endemic to Honduras.-Source:* Nelson, C. 1998. . Downloaded on 23 August 2007....

    , C. Nelson
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