Large-flowered hayweed

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Large-flowered hayweed
Large-flowered hayweed (Ludwigia grandiflora), population in France

Large-flowered hayweed ( Ludwigia grandiflora ), population in France

Systematics
Eurosiden II
Order : Myrtle-like (Myrtales)
Family : Evening primrose family (Onagraceae)
Subfamily : Ludwigioideae
Genre : Hay herbs ( Ludwigia )
Type : Large-flowered hayweed
Scientific name
Ludwigia grandiflora
( Michx. ) Greuter & Burdet
Five-fold, radial symmetry flower

The large-flowered hayweed ( Ludwigia grandiflora , Syn .: Ludwigia uruguayensis (Camb.) Hara ) is a species of hayweed within the family of the evening primrose family (Onagraceae).

features

Ludwigia grandiflora is a herbaceous plant that grows submerged in water ( submerged ), towering above the water surface ( emers ) or creeping over wet soil or mud (terrestrial). The above-ground shoots rooted at the nodes arise from a perennial, underground creep shoot ( rhizome ). The mostly reddish colored shoots reach a diameter of 5 to 20 millimeters and lengths up to 6 meters. The leaves are alternate . The leaf shape of the short stalked foliage leaves is extremely variable, there are all transitions between round-egg-shaped stalks about 4 to 5 centimeters long and about 1 to 2 centimeters long (often on submerged shoots) up to about 10 centimeters long, only 1 to 5 millimeters long-stalked, lanceolate, pointed leaves (often on air shoots). The stipules are elongated triangular and little glandular. Both shoots and leaves can range from densely velvety hairs to almost or completely bare.

The flowers stand individually in leaf axils of erect shoots, they have five narrowly lanceolate, 7 to 10 millimeter long sepals (sepals) and five (rarely up to seven) bright yellow colored petals (petals) and 10 (rarely up to fourteen) stamens . The length of the petals is 11 to 15 millimeters, never shorter than 10 millimeters. The flower tube is short, much shorter than the flower stem. The seed capsule is sub-cylindrical, 13 to 2.5 centimeters long, and narrowed towards the base, but not towards the tip, it is usually hairy, at its front end sit the perennial sepals. The seeds are enclosed in the hard, woody endocarp , their cross-section is triangular; they are about 1.5 millimeters long.

The flowering period in Europe extends from early summer to autumn, around June to September or October. each shoot produces a flower daily that has bloomed from morning to afternoon. In the south of France there are large stands that bloom but do not produce fruit; here the plants are self-incompatible and all functionally male; propagation takes place exclusively vegetatively via spreading. Populations further north develop fruits normally. The species is insect-pollinated; wild and honey bees, bumblebees and hoverflies have been observed as pollinators. A negative influence of the introduced populations on native plant species through pollinator competition could not be found, despite the sometimes extremely rich supply of flowers in the large stands.

Similar species

Of the similar Ludwigia peploides subsp. Which was also introduced to Europe but is more Mediterranean . montevidensis the species can be distinguished by the larger flowers (in Ludwigia peploides only up to 9 millimeters long), the shape of the stipules (in Ludwigia peploides kidney-shaped and strongly glandular), and the shape of the bracts (in Ludwigia peploides broader, more rounded and longer-stalked) . Ludwigia peploides has not yet been found in Central and Northern Europe. In the meantime, genetic markers have been published that allow these and other morphologically very similar species ( Ludwigia adscendens , Ludwigia inclinata , Ludwigia octovalvis , Ludwigia palustris , Ludwigia repens , Ludwigia sedioides ) to be differentiated using DNA barcoding .

Ludwigia grandiflora
Large-flowered hayweed ( Ludwigia grandiflora )
Mass population on the bank

ecology

Ludwigia grandiflora inhabits stagnant and slowly flowing, usually eutrophic bodies of water such as ponds, ponds, ditches, slowly flowing rivers and their oxbow lakes. The long flooding stems form numerous adventitious roots, which can absorb nutrients from the free water even without contact with the ground. When the water level drops, it can continue to grow on the dry bottom of the water and is also able to penetrate swamps and wetlands. In western France, the species has established itself in several regions, for example in the Brière Regional Nature Park on fen grassland that is flooded in winter. The development begins in spring when the overwintering creep shoots shoot. The first shoots often form floating leaves on the surface of the water. Later it can form impenetrable mats that can fill the entire volume of water. As a rule, it forms single species without the involvement of other aquatic plant species. Under favorable conditions, the shoots will straighten up later, and flowers will be formed on these straightened shoots. The above-ground parts of the plant are not hardy and usually die with the first night frost. The dead shoots with brown leaves can remain visible long into winter. Although of tropical origin, the species would be able to colonize almost all of Europe, north to north of Scotland, after habitat modeling ("climatic envelope" method).

Ludwigia grandiflora is able to colonize oxygen-free ( anaerobic ) bodies of water and muddy soils, for this purpose it has an air-conducting tissue ( aerenchyma ) in the roots. Although it prefers nutrient-rich waters, it can also establish itself in oligotrophic conditions. The species can damage competing plant species by releasing allelopathic secondary plant substances into the environment, as has been proven in laboratory tests. However, it is not known which substance is responsible for the effect.

The most important predators of the species in Europe are two neozoa: nutria ( Myocaster coypus ) and red American crayfish ( Procambarus clarkii ). The leaf beetle Altica lythri (Coleoptera, Chrysomelidae ) has also been observed on leaves. In its natural habitat (Argentina), a species of the fringed winged winged ( Thysanoptera ) has been identified, Liothrips ludwigi , which seems to specialize in the species.

Occurrence

Ludwigia grandiflora is naturally widespread in the New World in South and Central America , from northern Argentina to Guatemala, and in a separate ( disjoint ) sub-area in the southeast of the USA and Cuba.

The species was introduced as a neophyte to large parts of the USA and Africa ( Kenya ). In Europe, established occurrences from Belgium, France, Ireland, the Netherlands, Spain (coastal regions of Catalonia and Valencia) and Great Britain are reported. The only German occurrence so far was discovered in 2004 in the Leda , a tributary of the Ems in Lower Saxony, where it already developed large populations in 2009. In Switzerland there is currently a deposit near Geneva. Due to the ecological problems, Ludwigia grandiflora is listed on the black list of invasive species for Germany and Switzerland; in Switzerland, the plant is also prohibited from being placed on the market on the basis of the Ordinance on the Handling of Organisms in the Environment (Release Ordinance, RoSV).

Settlement and spreading of the species has been proven or presumably usually through displacement by humans, in particular the deliberate introduction or illegal disposal of aquarium or pond plants into the wild. The population in the Brière Nature Park was due to a mower that was not cleaned between operations; other technical devices such as trenches or anglers are also involved in the drag-out. However, it has been experimentally proven that even waterfowl such as the mallard, when grazing, carry seeds that are ingested and germinable in the faeces into new areas.

Taxonomy

The genus Ludwigia comprises more than 80 species and is distributed worldwide. Ludwigia grandiflora belongs to the Oligospermum section , a complex of (depending on your opinion) about 7 species with pantropical distribution. The species are very similar to one another, extremely variable with a wide overlap of features and occur in different ploidy levels (with different numbers of doubled sets of chromosomes). The taxonomy is therefore confused, numerous taxa , depending on the author, are understood as forms or subspecies of a species or as separate species.

Chromosome number

The clan introduced to Europe is decaploid (2n = 80) and is mostly called Ludwigia grandiflora subsp. hexapetala (Hook. & Arn.) GL Nesom & Kartesz . There is also a hexaploid clan (2n = 48) ( Ludwigia grandiflora subsp. Grandiflora ), which has not yet been found in Europe. The differentiation according to morphological features is difficult and uncertain. The flowers and leaves of the subspecies hexapetala are somewhat larger, the hairs are often somewhat sparse. However, the features overlap widely. But clans with the chromosome number 2n = 40 or 64 were also known.

Combat

The species is fought across Europe as a so-called invasive neophyte, which can seriously impair the biodiversity of the habitats it invades. In order to prevent further spreading, the trade in water plants for aquariums and garden ponds was targeted, where the species was at times sold as an "oxygen donor". The specialist trade responded from 2008 by attempting a voluntary commitment to stop selling. In the UK, a national plan of action on eradication has been drawn up.

Small colonies of newly established plants are controlled mechanically (by pulling out). Mowing the sprouts has no effect and rather stimulates growth. The plant can be killed with total herbicides , but this is associated with massive ecological disadvantages and is prohibited in most countries, including Germany.

The large-flowered hayweed was added to the “List of Unwanted Species” for the European Union in 2016.

swell

  • Philip S. Munz (1942): Studies in Onagraceae XII: A Revision of the New World Species of Jussiaea. Darwiniana T. 4, No. 2/3: 179-284. (sub Jussiaea uruguayensis )
  • Sophie Dandelot, Régine Verlaque, Alain Dutartre, Arlette Cazaubon (2005): Ecological, Dynamic and Taxonomic Problems due to Ludwigia (Onagraceae) in France. Hydrobiologia 551 (1): 131-136. doi : 10.1007 / s10750-005-4455-0
  • Alan S. Weakley: Flora of the Southern and Mid-Atlantic States. November 2012 version. download (54 MB) by The University of North Carolina Herbarium. Retrieved July 24, 2014.

Individual evidence

  1. ↑ Iris Stiers, Kjell Coussement, Ludwig Triest (2014): The invasive aquatic plant Ludwigia grandiflora affects pollinator visitants to a native plant at high abundances. Aquatic Invasions Volume 9, Issue 3 (online before print) download ( Memento of the original from August 1, 2014 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. @1@ 2Template: Webachiv / IABot / www.aquaticinvasions.net
  2. ↑ The Plant List: Ludwigia adscendens (L.) H. Hara
  3. ↑ R. Ghahramanzadeh, G. Esselink, P. Kodde, H. Duistermaat, JLCHvan Valkenburg, SH Marashi, MJM Smulders CCM van de Wiel (2012): Efficient distinction of invasive aquatic plant species from non-invasive related species using DNA barcoding. Molecular Ecology Resources 13 (1): 21-31. doi : 10.1111 / 1755-0998.12020
  4. ↑ Jacques Haury, Florian Noël, Michel Bozec, Julie Coudreuse, Jérémy Guil, Gaulthier Marrel, Jean-Luc Maisonneuve, Jean-Patrice Damien (2011): Importance or Ludwigia grandiflora as invasive weed on meadows and pastures in Western France. Author manuscript, published in "3rd International Symposium on Weeds and Invasive Plants, Ascona (CH): Switzerland (2011)"
  5. ↑ a b Plant Protection Service, Wageningen, NL and Center for Ecology and Hydrology - Wallingford, UK (editors): Ludwigia grandiflora (Michx.) Greuter & Burdet. A guide to Identification, Risk Assessment and Management. June 2011.
  6. ↑ a b c EPPO European and Mediterranean Plant Protection Organization (editor): Ludwigia grandiflora and L. peploides Onagraceae - Water primroses. EPPO Data sheets on invasive alien plants. EPPO Bulletin 41: 414-418.
  7. ^ Sophie Dandelot, Christine Robles, Nicolas Pech, Arlette Cazaubon, Regine Verlaque (2008): Allelopathic potential of two invasive alien Ludwigia spp. Aquatic Botany 88: 311-316. doi : 10.1016 / j.aquabot.2007.12.004
  8. ↑ María I. Zamar, María C. Hernandez, Gerardo A. Soto-Rodriuez, Axel P. Retana-Salazar (2013): A new Neotropical species of Liothrips (Thysanoptera: Phlaeothripidae) associated with Ludwigia (Myrtales: Onagraceae). Revista de la Sociedad Entomológica Argentina 72 (1-2): 83-89.
  9. ↑ Ludwigia. Identification key in Flora Iberica. Plantas vasculares de la Peninsula Iberica e Islas Baleares. online PDF
  10. ↑ Stefan Nehring & Detlef Kolthoff (2011): The invasive water primrose Ludwigia grandiflora (Michaux) Greuter & Burdet (Spermatophyta: Onagraceae) in Germany: First record and ecological risk assessment. Aquatic Invasions Volume 6, Issue 1: 83-89. doi : 10.3391 / ai.2011.6.1.10
  11. ↑ Distribution map for Switzerland at Infoflora.ch , accessed on July 27, 2014.
  12. ↑ Stefan Nehring, Ingo Kowarik, Wolfgang Rabitsch and Franz Essl (eds.): Nature conservation-related invasiveness assessments for non-native vascular plants living in the wild in Germany. BfN-Skripten 352, 2013 PDF
  13. ↑ Ordinance on the handling of organisms in the environment (Release Ordinance, FrSV), dated September 10, 2008 (as of June 1, 2012)
  14. ↑ CJ Luque, A. Garcia-Alvarez A. Perez-Vazquez, A. Velez-Martin, A. Hussner, AJ Green, EMCastellanoso Passive dispersal by waterfowl of seeds of Spartina densiflora and Ludwigia grandiflora, invasive species in wetlands and Mediterranean saltmarshes. 7th European Conference on Biological Invasions Halting Biological Invasions in Europe: from Data to Decisions Pontevedra (Spain) 12-14. September 2012. Abstracts: 252.
  15. ↑ Guy L. Nesom & John T. Kartesz (2000): Observations on the Ludwigia uruguayensis complex (Onagraceae) in the United States. Castanea 65 (2): 123-125.
  16. ↑ Ludwigia grandiflora at Tropicos.org. In: IPCN Chromosome Reports . Missouri Botanical Garden, St. Louis
  17. ↑ Alex Ploeg (2008): Invasive species in our industry? OFI Ornamental Fish International Journal 58: 21-25.
  18. ^ Department of the Environment, Food and Rural Affairs (2008): The Invasive Non-Native Species Framework Strategy for Great Britain. Department of the Environment, Food and Rural Affairs, London, UK 48 pp.
  19. ↑ List of Invasive Alien Species of Union Concern (PDF) accessed on July 15, 2016

Web links

Commons : Large-flowered hayweed ( Ludwigia grandiflora )  - Collection of images, videos and audio files