| Litsea | |
|---|---|
| Litsea monopetala Illustration | |
| Scientific classification | |
| Kingdom: | Plantae |
| (unranked): | Angiosperms |
| (unranked): | Magnoliids |
| Order: | Laurales |
| Family: | Lauraceae |
| Genus: | Litsea Lam. |
| Species | |
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200-400, including: |
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| Synonyms | |
Litsea is a genus of evergreen or deciduous trees or shrubs belonging to the Laurel family, Lauraceae. The genus includes 200 to 400 species in tropical and subtropical areas of both hemispheres.
Contents |
Trees or shrubs, dioecious. The ecological requirements of the genus, are those of the laurel forest 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. Litsea genus responde to characteristic formations of laurel forest. The natural habitat is forest or dense bush which are cloud-covered for much of the year. Several species are in danger of extinction due to over exploitation as medicinal plants or timber extraction and also for loss of habitat.
The patterns of speciation indicate that the majority of species is the product of vicariance. This is due to the current island like archipelagos of rainforests along the planet. The fragmentation of once more continuous rainforest facilitated isolation of populations and this likely caused the increase in the rate of speciation.
It has over 400 species worldwide in the tropical and subtropical regions of both hemispheres, 7 in Mexico and 3 in the Valley of Tehuacán-Cuicatlán. Distribution: Most species are found in Asia (300 species). The rest in Australia and the Pacific Islands and 8 in America. In North America from Mexico, crossing Central America, the southeastern United U.S. to Costa Rica. Northern South America, Australia, New Zealand, and Asia. China alone has over 70 species, mostly in warm regions of the south and southwest. Litsea merits revision and it is probably polyphyletic. The leaves can be either deciduous or evergreen depending on species, and aromatic. The flowers are from greenish to white, greenish-yellow, yellowish. Male and female flowers commonly are on different plants. The pollination is done by bees and other insects. The most striking are its fruits. The fruit is a small red, purple or black drupe containing a single seed, dispersed mostly by birds. Some species also reproduce vegetatively by stolons. Some species have strict ecological requirements and resistant habits, that can survive in conditions that are not appropriate, except wet lack, such as lack of light due to competition with other species but occurring too across a gradient of canopy cover including full sun , intermediate shade, and full shade. Most populations have been observed under closed overstory canopies of bottomland forests, and consequently, considered a shade-tolerant species, occurs also along the margin of a seasonally flooded depressional wetland but grow too in herbaceous zone with little canopy cover. The ecological characteristics of Litsea are similar to those of Lindera and are considered as a parallel evolution in Lauraceae.[1]Litsea is related to Adenodaphne a New Caledonian genus previously included, and Dodecadenia.
The genus includes species of trees, and shrubs, with evergreen foliage and inconspicuous flowers. The genus was more extended in the Tertiary and many species are adapted to laurel forest habitat. Lisea is adapted from sea level to more than 2000 meters with high mountain species. Litsea are dioecious and have mostly smooth, glossy, lauroide type leaves. Many are evergreen tree with some species growing to 25 m tall.
They have leaves alternates to opposite or rarely subverticillate, usually penninerved, rarely triplinerved, (3-ribbed); the inflorescences are consisting in pseudo-umbels (a flat-topped or rounded flower cluster) that are arranged in a racime, sometimes condensed, or a short-shoot or rarely sessile. Each pseudo-umbel with an involucre of decussate, crossed in the form of an X, usually persistent bracts. Leaves glabrous or pubescent, domatia absent.
Inflorescences axillary or solitary seudoumbelas along very short sharp branches, appearing racemose, covered before anthesis by an involucre of bracts decussate. rather campanulate, usually tepals 6, similar to one another, rarely unequal slightly extended, never papillose, soon deciduous, the male with 9-12 stamens, filaments well developed, internal glands baseline, anthers 4-sporangia, sporangia in 2 pairs almost vertical those of external whorl introrsas, those of inner whorl or extrorse latrorsas, hypanthium short and flat, vestigial pistilodio present;
The flower is from greenish, yellow to white. Male and female flower on different plants. The pollination is done by bee s and other insects. The flowers are irregular or trimerous. The flowers are unisexuals, male flowers with 5 to 20 fertile stamens. The female with a ovary globose, with 9-12 staminodes, urceolate hypanthium. the flowers could be without petals to nine petals by species. The petals when present are equal or unequal, often caducous during anthesis. In the stamens, several inner ones with glands.
Regularly, in the trimerous flowers there are three trimerous, up to 9 flowers. The third whorl with glands.
Filaments usually longer than the anthers. Anthers are having four locules. The pollen sacs arranged mostly in two pairs above each other, all introrse. Lower pollen sacs are latrorse. The staminodes usually are absent. The tepals usually are deciduous. The Pistillo or gynoecium well developed to absent. Fruits on a light or markedly thickened pedicel, supported by a shallow or deep dome, simple margin. The flower have a flat to deeply cup-shaped receptacle.The fruit is a drupe of variable shape and size. The most striking are its fruits, sometimes an ovoid berry, plum-like to olive-like drupe settled on a discoid small dome. With shape rounded or ovoid, brown to black, rarely green, purple, reddish, orange or yellow. The fruits are a very important food source for birds and other wildlife, like rodents, muntjacs, monkeys and bats. Most seeds pass through the bird's digestive system intact. Seed dispersal via ingestion by vertebrate animals, mostly birds and mammals, is the dispersal mechanism for most tree species.