Ravensara
Encyclopedia
The Ravensara is a Madagascar endemic genus of trees and shrubs flowering plants belonging to 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...

. Ravensare species produce Essential Oils from their bark, their leaves and their fruit.
The genus is composed of species native to central and eastern Madagascar
Madagascar
The Republic of Madagascar is an island country located in the Indian Ocean off the southeastern coast of Africa...

. In a recent generic classification of Lauraceae based on DNA sequence data by Chanderbali et al. in 2001, was found to be part of a strongly supported clade that also includes 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,...

, Potameia
Potameia
Potameia is a genus of plant in family Lauraceae. It contains the following species :* Potameia lotungensis, Kim Dao...

, Cryptocarya
Cryptocarya
Cryptocarya is a genus of evergreen trees belonging to the Laurel family, Lauraceae. The genus includes more than 350 species, distributed through the Neotropic, Afrotropic, Indomalaya, and Australasia ecozones.-Overview:...

, Endiandra
Endiandra
Endiandra is a genus of approximately 100 species of plants, mainly trees in the laurel family Lauraceae. They have a broad distribution across South East Asia, Australia and into the western Pacific Ocean....

  and Aspidostemon
Aspidostemon
Aspidostemon is a botanical genus of flowering plants belonging to the family Lauraceae. It is present from Madagascar.-Overview:The genus was described by Gunter Jens Rohwer & HGRicht. Published in Jahrbuch für Botanische Systematik, Pflanzengeschichte Pflanzengeographie und 109 : 74 in 1987...

.

Overview

The best known kind of Ravensara is Ravensara aromatica
Ravensara aromatica
Ravensara aromatica is a member of the Lauraceae family, and originates in Madagascar. The name ravensara is a latinization of the Malagasy word . Other Malagasy names include , and . The leaves and twigs of R. aromatica have a mildly camphorous aroma similar to eucalyptus. The essential oil of R...

. The essential oil extracted from its leaves is used for its medicinal properties. In Madagascar this genus of trees are commonly called Hazomanitra, tree that smells.They named local bark of Ravensara anisata Havozo.
Ravensara is a genus of evergreen laurel species that include currently more than 10 species, mostly 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. The genus Ravensara, endemic to Madagascar, was described by Sonnerat in 1782 with the single species Ravensara aromatica. Kostermans maintained Ravensara in his treatment of the Lauraceae for the "Flore de Madagascar et des Comores" and in a later publication from 1958 in which he described an additional nine new species of Ravensara. Currently, the estimated number of species of Ravensara is about 30.
Ravensara has always been considered closely related to Cryptocarya
Cryptocarya
Cryptocarya is a genus of evergreen trees belonging to the Laurel family, Lauraceae. The genus includes more than 350 species, distributed through the Neotropic, Afrotropic, Indomalaya, and Australasia ecozones.-Overview:...

. The malgache species placed in Ravensara and Cryptocarya are still poorly known, a transfer of all Ravensara species to Cryptocarya is not justified once revised the DNA isolation. Fisically in Ravensara the fruits are ruminate, whereas in malgache Cryptocarya they are not.

Characteristics

The genus includes 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...

 of evergreen
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, endemic from Madagascar and Comoro Islands
Comoro Islands
The Comoros Islands form an archipelago of volcanic islands situated off the south-east coast of Africa, to the east of Mozambique and north-west of Madagascar. They are divided between the sovereign state of Comoros and the French overseas department of Mayotte...

. The evergreen trees or shrubs in genus Ravensara are massive broad leaved evergreen trees growing 30 m tall. or slightly enlarged.
Common canopy trees to 30 m, sometimes very large to 60 m. or subcanopy trees in the succession climax species in tropical, lower temperate or subtropical broadleaved forest. Across communities of evergreen broadleaved forest and mixed coniferous-broadleaved forest. Found in low elevation evergreen forests and littoral rainforest, usually on all type of soils.

The trunk itself can grow to over a meter in diameter. Twigs angular, glabrous, terminal buds densely and minutely puberulous. The leaves are dark green and shiny.
The leaves are alternate, obovate to obovate-elliptic, 6-11 × 3-6 cm, glabrous, stiffly coriaceous, the base acute, rarely obtuse, margin flat, the apex rounded, the lower surface minutely but densely gland-otted,
lateral veins 4-6 on each side, reticulation raised on both surfaces, petioles glabrous, 9-14 mm long.
Inflorescences 3.5-9 cm long, paniculate, branched from the base, glabrous; bracts along inflorescences mostly deciduous, 1.5 mm long, linear, pubescent.
Flowers yellow-green, externally glabrous, tepals initially half-erect, in old flowers spreading, flowers 4-5 mm in diameter; pedicels short, from half the length of the floral tube to equaling it; having six tepals equal, narrowly ovate, 1.5-2 mm long, glabrous outside, puberulous inside; stamens 9, all 2-celled, pubescent, c. 1 mm long, the filament very short, 0.1-0.2 mm, the anther cells large, the connectives
slightly prolonged beyond the anther cells; stamens with the same length and width as the tepals and hidden behind them; 2 small globose glands present at the base of the inner three stamens; staminodia small,
narrowly ovate, pubescent; pistil glabrous, the style to 1 mm exserted, receptacle tubular, pubescent near the rim, otherwise glabrous.
Fruits are fleshy. The fruit, a berry, are an important food source for birds, usually this birds are from specialized genus: Columbidae, Turdidae, etc. Seeds are spread by birds. Birds eat the whole fruit and regurgitate seeds intact, expanding the seeds in the best conditions for germination (ornitochory
Biological dispersal
Biological dispersal refers to species movement away from an existing population or away from the parent organism. Through simply moving from one habitat patch to another, the dispersal of an individual has consequences not only for individual fitness, but also for population dynamics, population...

).

Only two species of Ravensara have the combination of glabrous twigs and leaves and raised reticulation on both surfaces of the leaves. Of these two, Ravensara macrophylla, only known from the fruiting type, differs in leaf shape (elliptic) and size (16-20 cm long). Like R. glabriflora, it has glabrous flowers, a feature unknown in other members of the genus on Madagascar, although flowers are unknown in 13 species.

Ecology

This genus reported for Madagascar and Comores Islands, have differences resultanting in ecological adaptations to different environments over a relatively dry-wet climate. 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. The Ravensara genus has led to endemic species on islands, but not so widespread geographically as in the past.

Ravensara genus is becoming endangered. Due to the low density, exploitation of the natural populations is in the detriment of the rainforest. The Ravensara genus is included in the Cryptocarya within the Lauraceae family, by Ravensara oil proposes. Some species have been used for a long time to produce essential oils for the pharmaceuticals industry.

The ecological requirements of the genus, are mostly those of the 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 like most of their counterparts laurifolia in the world, they are vigorous species with a great ability to populate the habitat that is conducive. Machilus responded to favourable climatic periods and expanded across the available habitat. The main centers are found inhabiting wet lands in tropical or subtropical 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...

 or coastal rainforest or coastal temperate forest in low-altitude. The islander Ravensara species can not enduring the bad winter, from continental climate. Those garden cultivated species outside its natural distribution could be killed by continental winter.

Species

It contains the following species, but this list is incomplete:
  • Ravensara glabriflora
  • Ravensara anisata (Airy Shaw) F.N. Wei & S.C. Tang
  • Ravensara aromatica
    Ravensara aromatica
    Ravensara aromatica is a member of the Lauraceae family, and originates in Madagascar. The name ravensara is a latinization of the Malagasy word . Other Malagasy names include , and . The leaves and twigs of R. aromatica have a mildly camphorous aroma similar to eucalyptus. The essential oil of R...

    Lecomte
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