Myriophyllum heterophyllum

Twoleaf Watermilfoil

The Twoleaf watermilfoil (Myriophyllum heterophyllum) is a perennial, mostly submerged freshwater plant that occurs in standing and flowing waters. The plant originates from North America and has established itself as an invasive species in many parts of Europe, Australia and New Zealand. It is characterised by long, pinnate leaves arranged in whorls along the stem. The leaves are dark green and can vary depending on growing conditions and environmental factors. Above water, differently shaped leaves often emerge than under water, hence the name "heterophyllum", which means "different-leaved". The flowers of the different-leaved centaury are small, greenish-white and appear from June to September. They are in the leaf axils and can be seen on short spikes above the water level. The plant reproduces both vegetatively by fragments of the plant and by seeds.

Types of damage

Ecological damage

Myriophyllum heterophyllum can form dense underwater stands that suppress native plants and reduce biodiversity. In addition, it can alter the nutrient dynamics of water bodies after dieback due to eutrophication, which can have an impact on local fauna and the ecosystem.

Economical damage

The formation of dense plant stands can block waterways, restricting boat traffic and other water-related activities. This can also affect recreational use of waterways and increase costs for water management authorities who need to control and combat the spread of the species.

Region of origin

North America

Introduction vectors

Pet trade (aquaristics)

Myriophyllum heterophyllum is a popular aquatic plant and was often bought for aquariums and garden ponds in the past. From there, it could enter the environment when the aquarium or pond was cleaned or drained and remnants of the plant got into nearby waterways.
Current distribution

Based on the FlorKart Database of the Federal Agency for Nature Conservation, as of 2013

Miscellaneous

Family

The Watermilfoil family (Haloragaceae) comprises about 8 genera with around 150 species. They are distributed worldwide, mainly in the temperate zones of the southern hemisphere. The family includes mainly aquatic and marshy plants, but occasionally also terrestrial species. Characteristic are the simple, often opposite leaves and the small, inconspicuous flowers, which are arranged in spikes or panicles. The best-known representative is the watermilfoil (Myriophyllum), which grows in stagnant or flowing waters and is often used as an aquarium plant. Under favourable conditions, some species can form invasive stands and dominate water bodies.

Climate change

Myriophyllum heterophyllum has not yet filled its potentially suitable habitat under current climate conditions. It benefits from climate change because in the future its potentially suitable habitat will increase. The environmental factors that most influence its spread are waterways, summer temperature, soil type, winter precipitation and winter temperature.

Dispersion forecast

Indicates the proportion of land suitable for habitat under current and future climate conditions (2060-2080) under three emission scenarios (RCP26, RCP45 & RCP85).

Habitat suitability maps

Instructions for use: Click here

Habitat suitability under current climate conditions

These habitat suitability maps show for Myriophyllum heterophyllum where suitable habitat conditions exist.

The map on the left shows this for current climate conditions. Below this are maps for the time classes 2040-2060 and 2061-2080, in which three different emission scenarios can be selected.

The slider at the top left allows you to adjust the opacity of the map to make orientation easier.

By clicking on the respective quadrant, information on the environmental conditions present in it can be called up.

The methodology is explained here .

Habitat suitability 2040 - 2060

2040-2060: In the RCP2.6 scenario, GHG emissions are expected to peak by 2040 through comprehensive mitigation measures and to decline rapidly thereafter. By 2060, global warming would stabilise at about 1.5°C above pre-industrial levels. Subtle changes in precipitation patterns could vary regionally, with some areas facing increased drought and others increased precipitation.

2040-2060: Under RCP4.5, GHG emissions would continue to increase until 2040, but stabilise at a high level thereafter. By 2060, there could be a global temperature increase of about 2°C above pre-industrial levels. This scenario would likely cause moderate changes in precipitation patterns, with potential regional differences.

2040-2060: Under RCP8.5, which assumes continued intensive use of fossil fuels, greenhouse gas emissions would rise sharply by 2060. The global temperature increase could be around 2.5-3°C. In this scenario, significant changes in precipitation patterns could occur, with an increased likelihood of extreme weather events.

Habitat suitability 2061 - 2080

2060-2080: By 2080, global warming could be limited to below 2°C in the RCP2.6 scenario, provided emission reductions are consistently pursued. Impacts on precipitation patterns would likely stabilise, although regional variance would remain significant.

2060-2080: In the RCP4.5 scenario, global temperatures would continue to increase and could be around 2.5°C above pre-industrial levels by 2080. Changes in precipitation patterns would likely increase and regional differences could become more pronounced.

2060-2080: Under RCP8.5, global temperatures could rise by more than 4°C above pre-industrial levels by 2080. Precipitation patterns would be expected to change significantly, with further increases in the frequency and intensity of extreme weather events. This would have far-reaching impacts on ecological and socio-economic systems.