Home page » Knowledge » Environment » Biodiversity » Neophytes

Neophytes

Neophytes (“new plants”) are plants that arrived in Switzerland in the 16^th century or later. Some of them spread very quickly as they have no natural enemies and/or enjoy better conditions than where they came from. These plants are called invasive neophytes. They displace native species – which means that the animals specially adapted to these species lose their habitat. This is why they should be combatted.

The law draws a distinction between a number of different categories.

Banned plants

It is not permitted to bring “banned plants” into circulation. In other words, they may not be imported, sold, transported or planted. Anyone who does so is liable to prosecution. These plants include ragweed, giant hogweed, Himalayan balsam, Japanese knotweed, American goldenrod and narrow-leaved ragwort.

Ragweed

Ragweed pollen can trigger very severe hay fever in people, extending right through to asthma and shortness of breath, including in people who have not suffered previously. Skin contact alone can also trigger allergic reactions. This is why it is important to:

wear gloves to pull out the plant along with its root (plus respiratory protection when the plant is in bloom)
dispose of all plant parts in the household waste
reseed the soil immediately

Giant hogweed

The giant hogweed is poisonous for people and animals. In conjunction with sunlight, the sap can result in severe burns and scarring that remains visible for a long time. It can also cause fever and circulatory problems, necessitating medical treatment. This plant likes to grow on riverbanks, with the water transporting the seeds to new areas. This is why it is important to:

mow close to the ground in April/May while wearing long clothing and gloves and avoiding skin contact with the sap
cut off the root 10-25 cm below the ground to prevent new shoots
dispose of all plant material in the household waste
frequently check the site

Himalayan balsam

A Himalayan balsam plant produces 4000 seeds each year that are shot up to seven metres away by the ripe seed pods. In the forest, this plant prevents natural rejuvenation and, on riverbanks, it promotes erosion. This is why it is important to:

pull out small stands together with the roots
mow large stands before flowering starts
check cleaned sites from May to July

Japanese knotweed

If things are going well, Japanese knotweed can grow up to 30 centimetres in a day. If it is chopped up, even the smallest of pieces can take root in the soil and produce new shoots. Combatting this plant is a real challenge and even the smallest plants must be disposed of. This is why it is important to:

mow every three weeks and dispose of all plant parts in the household waste
check cleaned sites from April to December

American goldenrod

Les stolons souterrains du solidage américain libèrent des substances toxiques dans le sol afin d’entraver la croissThe underground runners of the American goldenrod release toxins into the soil so as to make it difficult for plants to grow around then. This is why it is important to:

pull out individual plants from May to August – this is particularly easy after it has rained
mow large stands each year before flowering and before the seeds ripen
dispose of pieces of plant and roots in the household waste (they will survive being in the compost and you will spread them around the garden again)

A lot of people like the bright yellow flower head. Native alternatives are perforate St John’s wort, dense-flowered mullein and hemp-agrimony.ent les mêmes atouts.

Narrow-leaved ragwort / Common ragwort

The narrow-leaved ragwort or common ragwort is highly poisonous for people and animals. It is easily transported on vehicles, which is how it spreads. This is why it is important to:

pull it out with the root or mow it several times
dispose of all plant material in the household waste

Invasive potential

Other plants have “invasive potential”. They must be accompanied by handling instructions when they are sold, because they can spread uncontrollably if not treated correctly. These plants include buddleia (summer lilac) and cherry laurel.

Buddleia / Summer lilac

Buddleia or summer lilac is also known as the “butterfly bush”, because butterflies like to feed on its sweet nectar. Their caterpillars are much fussier, however, and because the summer lilac has displaced the plant they feed off, they are unable to find any food after hatching. This is why it is important to:

pull out young plants with their roots
cut down larger plants and dig out rootstocks – always dispose of them in the household waste
check cleaned sites from April to October

Cherry laurel

With its evergreen leaves, the cherry laurel is a popular privacy screen for sitting areas in the garden. All the different parts of the plant are poisonous, however, especially the berries which are attractive to children. Birds tolerate them well, however, and spread the seeds with their droppings. This is why it is important to:

cut off the inflorescences before the seeds ripen
pull out young plants with their roots
remove older shrubs together with the rootstock
Dispose of all the plant material in the household waste

The following plants can be used to form native privacy hedges: common beech, European holly, European yew, ivy.es pouvant aussi former des haies végétales et ainsi protéger des regards indiscrets.

High damage potential

Other species have a high damage potential, but it is impossible to control their spread, because they are dispersed very rapidly, for example. These include the annual fleabane.

Annual fleabane

Each annual fleabane plant forms at least 10,000 seeds which are dispersed in the area around it by the wind. Scarcely any animals eat the plant. This is why it is important to:

pull out plants by hand – don’t mow them, because they then form a “felt”, which is much more difficult to pull out
check cleaned sites from April to October

Evening primrose

It is not clear how the evening primrose is to be classified. Experts feel that it is becoming increasingly common, which is why it is sometimes listed with the above plants. At the same time, there would not appear to be any scientific basis to suggest it has damage potential or spreads uncontrollably. But it certainly doesn’t do any harm for people to combat the evening primrose on their own land.