Botanist Gertrud Lohaus on the common dandelion

Mrs Lohaus, what kind of plant is the common dandelion and where does it originally come from?

Lohaus: That's not so easy to answer. My colleague said "everyone knows it, but nobody recognises it" or "everyone recognises it, but nobody knows it", whichever you prefer. Botanically, this little plant is a real heavyweight.

Dandelion here refers to Taraxacum, a plant genus. This genus belongs to the Asteraceae plant family. It is called asteraceae because the supposed flower of the dandelion is a basket of flowers that simulate a single flower. The best-known representative in our country is probably the common dandelion, which is known as Taraxacum section Ruderalia. It is therefore not a single species, but a whole group of similar species or subspecies within the genus Taraxacum.

The populations of the common dandelion cannot be defined as a species, as they "go beyond" the biological species concept. There are many similar plant groups as well as many transitional forms. Nevertheless, certain plant groups cannot interbreed with others, which actually makes them each a separate species. This "inability to interbreed" is due to the fact that the plants have a genetic peculiarity, as many not only have a double set of chromosomes, but a triple or even quadruple set. This is why the plants are collectively referred to as the Ruderalia section. There are also differing opinions about the number of species belonging to this section. Some assume a few species, others define several hundred species! And all of them are common dandelions.

The common dandelion originates from Europe and western Asia, but is widespread throughout the northern hemisphere. Dandelions can be found in many meadows and pastures, especially if they have been heavily fertilised with manure or artificial fertiliser. Dandelions tolerate a lot of nitrate. However, dandelions can also be found in many other places, in cracks in walls, on roadsides and here on campus in a wide variety of places.

Dandelions are often seen as annoying weeds, but the plant with its long roots is actually very important for our soil. Why is that?

Lohaus : I don't know whether dandelions are really more important for the soil than other plant species. Thanks to its long taproots, dandelion can also get water from deeper layers.

It has more vitamins than any other vegetable. Even the iron content of dandelion is 30 times higher than that of spinach. Is that true?

Lohaus: I would be careful with statements like that. Which vitamins are we talking about? Many green vegetables are rich in vitamins, e.g. kale. In addition to the species or variety, it naturally depends on where the plant grows, under what conditions, etc. This means that there can be huge differences in content.

The animal world also benefits from it. How?

Lohaus: Dandelions provide food for many insects in the form of pollen and nectar. Other herbivores utilise the leaves. Children who have rabbits as pets usually also look for dandelions for them.

Dandelion is one of the most vitamin-rich wild plants in our region. What can it be used for?

Lohaus: As I said, I doubt whether it is the richest in vitamins? Not all species have been analysed. The young leaves of the dandelion can be used as a salad. As dandelion is somewhat bitter, it is usually only part of the salad. Incidentally, our "lettuce" and many other types of lettuce also belong to the Asteraceae family, i.e. the same plant family.

In terms of flavour, dandelion lettuce is comparable to radicchio or chicory because it contains taraxacin. This has also earned it its inglorious nicknames such as piss flower and bed-wetter. What does it do to the body?

Lohaus: Dandelion has a diuretic effect. Unfortunately or fortunately, I can't say how strong this effect is as I have never consumed such large quantities. The substances in the dandelion that trigger this are not yet fully understood. Taraxacin as a bitter substance is described more as a stimulant for digestion and not necessarily in connection with "diuretic".

As bitter as the leaves are, the flowers are all the sweeter. Why is that?

Lohaus: There is sugar in the petals and flower nectar is also sweet. Leaves naturally also contain sugar and correspondingly larger quantities of bitter substances.

You can even make your own coffee from the roots, which has a which tastes somewhat malty, nutty and bitter, depending on when the roots are harvested. In times of sustainability, the plant is actually an all-rounder, isn't it?

Lohaus: The roots contain a substance called inulin (a polymer made from fructose). When this substance is roasted, it gives a malty flavour. Other plants that are used for malt coffee also contain this substance, e.g. chicory (chicory). I'm not such a fan of malt or grain coffee myself. I prefer a cup of "real bean coffee" or an espresso/cappuccino. Of course, this is a matter of taste; in any case, dandelion does not contain any caffeine.

The stalks have a whitish milky sap which, according to a press release from the Fraunhofer Institute (IME), could now also be used as an adhesive. Quote: "We have found the enzyme responsible for rapid polymerisation and have switched it off," says Prof. Dr Dirk Prüfer, head of department at the IME.
"If the plant is damaged, the latex flows out instead of polymerising. We obtain around four to five times the usual amount. If the plants were grown on an industrial scale, 500 to 1,000 kilograms of latex could be produced on one hectare per growing season." So that's how natural rubber could be produced in Europe in the future, right?

Lohaus : That sounds good at first, but it would have to be calculated whether it is worthwhile and what else needs to be considered during production.

What characteristics do you value in dandelions?

Lohaus : As a child, I often picked the dandelions and even today I still find it fascinating how the seeds fly through the air with their little "umbrellas".

Uwe Blass

Prof Dr Gertrud Lohaus took over the professorship for Molecular Plant Research/Plant Biochemistry at the University of Wuppertal in 2009