Ligustrum robustum
| Ligustrum robustum | ||||||||||||
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Ligustrum robustum subsp. walkeri |
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| Ligustrum robustum | ||||||||||||
| ( Roxb. ) Flower |
Ligustrum robustum is a plant of the genus Ligustrum within the family Oleaceae (Oleaceae). It has indigenous occurrences in Southeast Asia and has been planted many times outside of its natural habitat and has grown wild there. Neophytic occurrences on the Mascarene archipelago, especially on the island of Réunion , are considered to be a serious threat to biodiversity . Ligustrum robustum was therefore included in the list of 100 of the World's Worst Invasive Alien Species of the International Union for Conservation of Nature ( IUCN ).
description
Vegetative characteristics
Ligustrum robustum is a shrub or small tree with a maximum height of 5 to 8 meters. Young buds are hairy or glabrous.
The opposite arranged leaves are divided into a petiole and a leaf blade. The petiole is 0.2 to 1.5 inches long. The somewhat leathery, bald, simple leaf blade is 4 to 8 (up to 14) centimeters long and 2 to 6 centimeters wide and is elliptical-lanceolate with a wedge-shaped blade base and a spiked upper end, the leaf margin is entire. The five to nine pairs of leaf veins are slightly protruding on the underside.
Generative characteristics
The flowers sit in groups in terminal racemose to zymous inflorescences 5 to 20 centimeters in length, rarely above, which are hairy to almost bald. Bracts are usually absent, if they are present, they are ovate or lanceolate with a length of 0.5 to 1.5 millimeters. The downy, hairy flower stalk is 1 to 3 millimeters long.
The flowers are 5 to 6 millimeters long. The hermaphrodite flowers are radial symmetry and four-fold with a double flower envelope . The bell-shaped calyx has a calyx tube less than 1 millimeter long and 1 to 2 millimeter long calyx lobes, it is bald. The four white, 3 to 5 millimeter long petals are fused into a 1 to almost 2 millimeter long corolla tube.
The cylindrical, single-seeded stone fruit is 7 to 10 millimeters long and 3 to 6 millimeters in diameter kidney-shaped to ovoid or obovate and is almost always asymmetrical . The fruits are blue-purple when ripe.
ecology
Ligustrum robustum , like many privet species, can also spread vegetatively via rooted runners.
The diaspores are spread by birds.
Systematics
Ligustrum robustum was first described by William Roxburgh in his work Flora Indica , as Phillyrea robusta in 1820. In 1850, Carl Ludwig Blume transferred them to the Ligustrum genus .
The taxonomy of this species is confused. In India in particular, there are numerous variable privet clans with an overlapping spectrum of characteristics, which various botanists have perceived as independent species or as subspecies of a broad collective species Ligustrum robustum .
Usually the following subspecies are distinguished:
- Ligustrum robustum (Roxb.) Flower subsp. robustum : It is common in northeast India , Bangladesh , Myanmar , Thailand , Laos , Vietnam and Cambodia .
- Ligustrum robustum subsp. walkeri ( Decne. ) PSGreen : You are endemic to Sri Lanka and as a neophyte is widely abducted and naturalized.
The status of the following subspecies is controversial:
- Ligustrum robustum subsp. chinense P.S. Green : It is common in China. Possibly it is a synonym of the species Ligustrum expansum
- Ligustrum robustum subsp. perrottetii ( A.DC. ) de Juana .: It occurs only in southwestern India. Many botanists regard this clan as an independent species.
Locations
Ligustrum robustum is considered a penumbra plant, it can grow in the shady undergrowth of forests, but needs more exposure to bloom and fruit. It grows in moist to fresh locations, often along the banks of running water, and can establish itself well in disturbed locations such as roadsides. It is a type of hill country up to the submontane altitude level at altitudes of about 725 to over 1500 meters.
Occurrence on the Mascarene Mountains
The species Ligustrum robustum was originally introduced as an ornamental shrub to the island of Mauritius at the beginning of the 20th century, and only much later to Réunion, where it became wild. Today it not only occurs in vegetation units disturbed by humans, but is also able to successfully penetrate the small remains of natural vegetation on the islands and displace native plant species there. This is a problem for species protection, especially on Réunion, as extensive remains of the original vegetation have been preserved on this island (approx. 75,340 hectares , which is around 30 percent of the original area). On Mauritius the species already forms very extensive, almost impenetrable, monoculture- like thickets that, together with some other neophytes, are superior to and displace the native flora in the competition, a corresponding development has also started on Réunion. Ordinary protection measures, such as the designation of the Réunion National Park, cannot stop the species that birds spread. The introduced plants are Ligustrum robustum subsp. walkeri , the involvement of other clans via introgression was excluded on the basis of genetic studies.
Ligustrum robustum is mainly controlled mechanically, by digging up or tearing it up. Herbicides are also used. Some natural antagonists are being tested for biological control, but this is not yet ready for use.
Individual evidence
- ^ A b José Ignacio De Juana Clavero: Taxonomía actualizada del género Ligustrum L .. In: Bouteloua , Volume 6, 2009, pp. 16-71.
- ^ A b Peter Shaw Green: Synopsis of the Oleaceae from the Indian Sub-Continent. In: Kew Bulletin , Volume 58, Issue 2, 2003, pp. 257-295. JSTOR 4120616
- ↑ a b c d e Global Invasive Species Database = GISD , 2015: Species profile Ligustrum robustum. online , accessed January 5, 2017.
- ↑ a b RI Milne, RJ Abbott: Geographic origin and taxonomic status of the invasive Privet, Ligustrum robustum (Oleaceae), in the Mascarene Islands, determined by chloroplast DNA and RAPDs. In: H eredity 92, 2004, pp. 78-87. doi: 10.1038 / sj.hdy.6800385
- ^ Qin Xiang-Kun: A New System of Ligustrum (Oleaceae). In: Acta Botanic Yunnanica , Volume 31, Issue 2, 2009, pp. 97-116.
- ↑ José Ignacio De Juana Clavero (2015): Posible resolución del dilema Ligustrum perrottetii: propuesta de Ligustrum robustum subsp. perrottetii (A. DC.) comb. nova. In: Bouteloua , Volume 20, pp. 3-15.
- ↑ Christophe Lavergne, Jean-Claude Rameau, Jacques Figier: The Invasive Woody Weed Ligustrum robustum subsp. walkeri Threatens Native Forests on La Réunion. In: Biological Invasions 1999, 1, p. 377. doi : 10.1023 / A: 101000152922
Web links
- Lien-ching Chiu Chang, Zhi Wei, Peter S. Green: Oleaceae. : Ligustrum robustum subsp. chinense , p. 302 - the same text online as the printed work , In: Wu Zheng-yi, Peter H. Raven (Ed.): Flora of China , Volume 15 - Myrsinaceae through Loganiaceae , Science Press and Missouri Botanical Garden Press, Beijing and St Louis 1996, ISBN 0-915279-37-1 .