Ludwigia peploides
Ludwigia peploides is a species of flowering plant in the evening primrose family known by the common names floating primrose-willow and creeping water primrose. It is native to Australia, North America, and South America, but it can be found on many continents and spreads easily to become naturalized. It is well known as a troublesome aquatic noxious weed that invades water ecosystems and can clog waterways. This is perennial herb which grows in moist to wet to flooded areas. The stem can creep over 2 meters long, sometimes branching. It spreads to form mats on the mud, or floats ascending in the water. The leaves are several centimeters long and are borne in alternately arranged clusters along the stem. The flower has 5 to 6 lance-shaped sepals beneath a corolla of 5 or 6 bright yellow petals up to 2.4 centimeters long. The fruit is a hard, cylindrical capsule.
Distribution
Ludwigia peploides is native to Australia, North America, and South America.In the US
In the US it can be found predominately along the east and southwest coasts.In Europe
L. peploides has established a significant presence as an invasive species, and has caused serious problems in areas where it has been introduced, presenting challenges to ecologies and infrastructure. In France, L. peploides now tops the list of the most invasive aquatic plants in the nation.An estimate of its areas of heaviest dispersion might be gleaned from records of public action against it. Bans on the trade of L. peploides have been enacted in the contiguous nations of France, Netherlands, and Belgium, as well as in United Kingdom and Portugal, and there are reports that it has now also been found in Croatia.
Habitat, ecology and dispersal
The genus Ludwigia is present worldwide. There are 23 sections consisting of 82 species in total. They can be both woody, herbaceous and aquatic. They have very high levels of reproduction and efficient dispersal capacity which is a large factor in its ability to take over habitats all across the world.Their reproduction is divided into four steps that coincide with the changing seasons. During the spring, new shoots form buds. If in shallow water, it is formed in an erect position, but if in a drained environment, they will adopt a creeping form. The stems will eventually rise to the waters surface and will then form rosettes and small round leaves. The next step occurs over the summer where apical and branches begin to form whether the species formed in an erect or creeping form. After an overall lateral extension of 50 cm flowers can begin to emerge. Between late June to early October, yellow flowers are produced and reproduction can occur. The sexual reproduction of these plants are relatively unknown due to lack of research and can vary from species to species. In autumn, from August to November fruiting occurs. For the rest of the year, the winter months, the species will break up, dry out and decay but it has been seen that there are cases where it can survive.
Because Ludwigia can propagate from stem fragments or rhizomes broken off by wind, water flow or animals, they have been scattered across the globe. They can be broken as easily by wind, water flow or animals. Fragments of Ludwigia peploides can double in biomass in between 15 and 90 days. This allows this species to thrive in habitat and regions where sexual reproduction cannot occur.
The Ludwigia occur predominantly in wetlands and in the transition areas between aquatic and terrestrial environments. As a result of their high plasticity, Ludwigia can colonize almost anywhere in slow flowing waters, river banks and wet meadows. They prefer slow flowing water over water with a higher velocity. Most Ludwigia species where present in stagnant water, from.06 to 1 metre deep. Great depths became a constraint on their development but shoots were still able to form flower buds. If they are in a low nutrient condition, Ludwigia double their biomass. The only true weakness of this species is intense levels of salinity in the water they inhabit.