Asclepias syriaca

Common milkweed

Asclepias Syriaca, also called common milkweed, reaches heights of up to two metres. Its leaves are lanceolate, dark green and covered with fine hairs. The flowers, which appear between June and August, are pink to purple and arranged in dense umbels. The scent of the flowers is intense and attracts many insects. After flowering, the plant forms elongated fruit capsules that release a large number of seeds when ripe. The seeds are equipped with long, white fibres that serve as a flying apparatus and facilitate dispersal by wind. Due to its high adaptability, Asclepias syriaca can dominate in different habitats and suppress local species.

Types of damage

Ecological damage

As an invasive species, Asclepias syriaca is very adaptable and can dominate in different habitats. It displaces endangered native species, such as sand catchfly or phleum arenium. This can lead to a decline in biodiversity, especially in sandy grassland communities.

Economical damage

On agricultural land, Asclepias syriaca can lead to yield losses as it suppresses other crops. This is especially relevant for vineyards and orchards, where it competes with young tree plantations for resources.

Damage to health

Although Asclepias syriaca is not usually considered harmful to human health, it can cause allergic reactions in some individuals. In particular, the milky sap of the plant can cause skin irritations. In addition, consumption of the plant, especially by children or pets, can be toxic as it contains cardenolides that can cause digestive problems and, in the worst case, heart problems.

Region of origin

North America

Introduction vectors

Horticulture

Asclepias syriaca has been planted as an ornamental plant in gardens and parks. From there it has been able to spread into the surrounding landscape.

Agriculture

The seeds of the plant can be carried by agricultural machinery and vehicles moving from an infested to a non-infested area.
Current distribution

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

Miscellaneous

Family

The dogbane family (Apocynaceae) comprise about 366 genera with about 5100 species. They are mainly distributed in the tropics and subtropics and include shrubs, trees, lianas and some succulent species. A characteristic feature is the milky sap, which is present in many species and often contains toxic alkaloids. The flowers are often showy and the fruits usually pods containing many seeds with hair crowns. Important representatives are the oleander, various Stephanotis species as ornamental plants, Jatropha curcas as a source of biofuel and Rauwolfia serpentina, from which drugs against high blood pressure are obtained.

Climate change

Asclepias syriaca 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 soil type, road infrastructure, precipitation in summer, rail infrastructure and temperature in summer.

Positive effects

Due to its popularity with bees and butterflies, Asclepias syriaca has been used in beekeeping and as an ornamental plant. In the past its milky sap was also used for rubber production, but today this plays a minor role - as does its use as a medicinal plant.

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 Asclepias syriaca 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 beschrieben.

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.