The cannabis plant contains the psychoactive substance tetrahydrocannabinol (THC). It makes people feel euphoric and relaxed and can also alleviate pain. The flowers of infertilized female plants contain particularly high amounts of THC, that's why they are taken for producing marihuana. Some cannabis species do not contain any THC at all and are grown for fiber production.

Opium poppy (Papaver somniferum) produces - you guessed it - opium. To harvest it, you simply incise the capsules and let the white latex exude and dry. Opium contains high amounts of morphine, the strongest existing pain medication. A chemical variation of morphine provides the semi-synthetic drug heroin.

Mushrooms are chemical artists - some of them even produce psychoactive substances. Among them: this grey-coloured Pluteus salicinus. It grows on wood and contains psilocybin, which causes visual and mental hallucinations similar to LSD. Side effects are nausea and panic attacks.

Leaves of the coca plant harbour chemical compounds similar to cocaine. They alleviate pain and act as stimulants. In many countries in Latin America, chewing on raw coca leaves is quite common. It helps tourists deal better with altitude sickness, too. By fermenting and drying the leaves and processing them chemically, cocaine is produced.

Angel's trumpets are beautiful to look at but you should refrain from tasting them. All parts of the plant contain alkaloids - chemical compounds with strong effects on the human body. When you eat or smoke the plant, your heart rate will increase and you will start to hallucinate. As with all natural drugs, finding the right dosage is difficult. Deadly accidents occur quite often.

On the internet, poisonous Datura plants - also known as thornapples - are advertised as natural drugs as well. Really not a good idea: The plant induces strong hallucinations, sometimes with a complete loss of reality. People tend to hurt themselves severely under its influence.

Argyreia nervosa is native to Asia, even though the plant is called Hawaiian baby woodrose. The seeds of this climbing vine contain ergine, a compound similar to LSD. It causes colourful visions and euphoria but also nausea, prickling and psychoses. Overdosing can happen easily as one seed alone already has a strong effect.

The peyote cactus in Mexico and Texas is full of mescaline, a hallucinogenic compound that is illegal under the international Convention on Psychotropic Substances. Mescaline alters thinking processes and one's sense of time and self-awareness. The cactus is cut into pieces and eaten or boiled into a tea. The cactus species is now listed on the Red List as vulnerable.

Nutmeg in high amounts can act as a drug, since it contains the hallucinogenic compound myristicin. But don't worry: you'll never reach the necessary dosage if you only use nutmeg as a spice. Getting high on nutmeg seems a bad idea anyway, as side effects include headaches, nausea and diarrhea.

Yes, it's true: the evergreen kratom tree (Mitragyna speciosa), native to Southeast Asia, incorporates the opioid-like compound mitragynine into its leaves. In traditional medicine, the leaves are chewed to relieve pain, increase appetite and treat diarrhea. But they can also be used to mix drug cocktails.

The tobacco plant produces poisonous and addictive chemicals, such as nicotine and other alkaloids, and harbours them inside its leaves. With this poisonous cocktail, the plant tries to ward off animals that might want to eat it. When the leaves are dried and smoked, the chemicals enter the human body - together with many cancerous substances generated by burning tabacco.