Botanical Accuracy: Common mistake: Centaurea vs. Centaurium, both centaury

Monday, June 3, 2013

Common mistake: Centaurea vs. Centaurium, both centaury

The two plant genera Centaurea and Centaurium are commonly mixed up, even if they are very different and belong to different families. Species in Centaurium have the common name centaury in singular, and centauries in plural, and unfortunately you often see this common name in herbal literature or in online sources for Centaurea too.

CENTAURIUM (centaury) is a member of the gentian family, Gentianaceae. This genus has about two dozen species, and they are nearly all bright pink. The flowers have 5 petals, and are small, up to 1.5 cm (1/2 inch) across. (An image search for Centaurium shows all the varying flower types.)

Centaurium pulchellum
(cc) Christian Fischer, Wikimedia.

CENTAUREA (knapweeds, cornflowers, star-thistles, etc.) is a member of the sunflower family, Asteraceae. There are hundreds of species in this genus, and they all have small feathery-looking flowers assembled in a tight flower head. The petals can be white, blue, pink, or purple. The flowers along the edge are longer, and the ones in the center of the flower head resembles thistle-flowers, and they are closely related to thistles. (Image search showing the flower variation of Centaurea.)
The similarity of the genus name Centaurea to Centaurium leds to confusion and the misapplied "centaurium" as a common name.

Centaurea montana
(cc) Jean-Pol Grandmont, Wikimedia

Other differing characters are that Centaurea usually has alternate leaves (Centaurium have opposite leaves) and the flower heads are larger in Centaurea than the single flowers of Centaurium.

So, why do we need to care which centaury that is in the herbal medicine, or reported? Well, to begin with, these plant groups have completely different chemicals in them. And for herbal medicine, it is the chemicals that we want, and we want the right ones. Second, if we suggest to people to use these plants, you better have the right photo (and ingredient) for the plant you intended. Third, it is just simply embarrassing if you are a company or publisher and gets this wrong. It is a classic example of why common names can be troublesome if you want to be sure about what plant that was used.

Here are some examples of where companies or other sources of information got it wrong:

Medicinal Herb Info: Talks about Centaurium, but lists bluet and bluebottle as alternative common names, but those two names are only used in Centaurea.
Specialty Herb Store: Same problem as above, lists common names only present in Centaurea for the medicinal Centaurium plant.

Post updated 28 January 2014 with information provided by MF.

What is Botanical Accuracy?

Would you care if someone called a cat 'a mouse' in the description of a medieval painting?

Would you care if someone served you horse meat, but said it was beef? I bet you would.

Would you care if the wrong chemical was listed in the ingredient list of your shampoo or cereal?

Would you care if you bought one plant, but got another?

Would you care if there were species or ingredient mistakes in advertising, menus, herbal pills, and such things?

Would you care if books on plants are illustrated with the wrong plants?

If so, here is the place for you to read about such problems in the world of plants and plant products, where unfortunately such mistakes, inaccuracies, and problems are not uncommon. This is usually due to lack of botanical knowledge or expertise, or sometimes because of plain ignorance.

Inaccuracies are common when it comes to plants, because it seems like we humans care to learn less about green things like trees, flowers, and herbs than we care to learn about animals, even when we eat plants, paint them, plant them, extract their chemicals, or use them in numerous other ways.

Without plants in the world you and I certainly would be dead. Some plants can also kill you with their toxins, so it is best to know which plant is what species. Time to learn some botany!

About mistakes, inaccuracies, and errors

Science is a process of gaining knowledge and understanding of the world around us. It is a never-ending process, and what we think are true facts today might change tomorrow. In science we are aiming for having the best understanding possible today based on what we and our predecessors have learned until now.

This means that what is botanically accurate from a scientific viewpoint might (and will) change. Other experts in the field of botany know a lot more about their particular research plants than I do. New scientific findings and conclusions are being published every day. This is just normal and part of the scientific process; we improve on our knowledge all the time.

The important thing is our willingness to continuously aim for botanical accuracy and the highest scientific standards in our use of names and facts. When things are wrong, let's correct them. Let us not perpetuate wrong botanical knowledge by accepting its incorrect use on commercial products, in everyday language, or in other parts of our contemporary cultures. Through scientific education and specific corrections we will improve botany and science for everybody, in supermarkets, restaurants, and garden centers.

It is the perpetuation of incorrect facts that are the problem, not the need for correction. Everybody makes mistakes, and everybody learns, throughout their lives. We need words to be able to communicate and talk about things, so let's use the right words and the right species names.

Undoubtedly there will be mistakes and errors on this blog, or things that need to be updated. If you want to get in touch, please e-mail me at botanicalaccuracy at gmail.com. If you see a mistake on this blog, e-mail me with the link to the post and an explanation what is incorrect and should be updated. If you represent a company and want to get in touch, please use the same e-mail address.