To all botanists and herbologists out there: Milk Thistle - Silybum marianum or Carduus Marianus?

Question

And if they are the same, when should each name be used? Also, for some inexplicable reason I used to think milk thistle belongs to Compositae familiy and just now found it in Wikidepia as Asteraceae. What's right?

Answer 1

The name "Milk Thistle" can apply to many species in a particular sub-group of the Asteraceae. These (strangely enough) have a milky juice. Lettuce and Dandelions are also Asteraceae that have milky juice (altho not thistles as such).

Compositae family and Asteraceae are the same thing. There are a small number of families that have two accepted names ... one a sytematic name (stem of the name of the type genus with the ending -aceae tacked on) and the other based on a descriptive term (usually with only -ae tacked on). So:

Compositae (the daisy family) = Asteraceae
Palmae (palm family) = Arecaceae
Umbelliferae (carraway family) = Apiaceae
Gramineae (grass family) = Poaceae
Leguminosae (pea family) = Fabaceae

plus a few others. These were so familiar that the botanical name rule book gives special approval for the names to be used interchangeably. So both are right.

Answer 2

This often happens. The proper name is the Carduus, but Silybaum is a synonym, an alternative that used to be a lot, and a lot of people still do. It's like Apatosaurus / Brontosaurus in dinosaurs. botanists thought it was in one family, then realised they got it wrong, so shifted it somewhere else.

I would have thought the same as you, so I just had a quick google, and is seems that the Compositae are now called asteracea. More meddling!!

Incidentally, the cardoon is Cynara cardunculus, also called the artichoke thistle, as it looks similar to a globe artichoke.

Answer 3

Silybum marianum & Carduus marianus are the same plant. As I understand it the name used to be Carduus marianus and seems to have been superceded somewhere along the line by Silybum marianum. As a herbalist I learned it as Carduus marianus and the various suppliers of my herbs seem divided on the issue. I prefer Carduus and look forward to the day that botanists quit meddling with names for what appears to be the sheer hell of it. Maybe they could focus on getting the right name for new plants from their point of discovery rather than picking a best fit and changing it later on.
There is some interesting info on it and some nice pics at http://www.herbs-hands-healing.co.uk/singleherbs/milkthistle.html

Answer 4

Milk Thistle is definitely the Silybum one; don't know if it's an Aster or not. Isn't Carduus the Cardoon?

Answer 5

relax. these are all synonyms.
Asteraceae=Compositae, Sillybum marianum=Carduus marianus.
Compositae and Carduus marianus are older names, so dont use these if you want to be 100% correct.