Botany Photo of the Day

Is there anything good or beneficial about this plant?

Claimed to be effective against liver diseases, but “Milk Thistle: Effects on Liver Disease and Cirrhosis and Clinical Adverse Effects” suggests that is not yet proven: “Clinical efficacy of milk thistle is not clearly established.”

"Beneficial," like so many of the adjectives we use, is a subjective term. Whether there's any benefit to growing Silybum marianum in a region where it becomes invasive or in an area where there are livestock is not the question; it is clearly an idea without much merit in such places. Elsewhere, however, where it is safely grown as an ornamental (are there any places left?), it can be beneficial in the sense that it brings pleasure to the people looking at it. Personally, I would encourage people to grow it (where it isn't a threat to the local ecology) just for its name. The name silybum was Dioscorides' name for a thistle-like plant, and marianum refers to the Sierra Morena in southwestern Spain. Just don't tell a kid that stuff.

I am curious about the post relating to the species Silybum marianum stating that 'marianum refers to the Sierra Morena in southwestern Spain.' Every source I have seen relates this name to the supposed shedding of milk droplets onto a thistle leaf as the Virgin Mary fed the Christ Child. Its various common names such as holy thistle, Mary's thistle, Our Lady's thistle, milk thistle and blessed thistle, seem to support this derivation, at least as far as that species is concerned. Stearn's Dictionary of Plant Names says that it has also been used in other species to allude to the state of Maryland which at one time was referred to as Terra Mariana, but I don't know of any taxonomic names that would have this etymology.

I was excited to see a medicinal herb featured with such beautiful photos today. Milk thistle seed extracts are drugs used in european emergency rooms to detoxify the neurotoxins in Amanita mushroom poisonings. Sometimes it seems the Atlantic ocean is really an information gap. Silimarin is believed to be the compound that has hepatoprotective effects, and may bind with certain alkaloids to help them detoxify. This herb is also not the same as blessed thistle.
I am particulary interested in non-native invasive species, and was unaware that milk thistle was one. Thanks for the references!

PTowler is correct in saying that blessed thistle is not the same as milk thistle, however as is frequent with common names, there is no absolute right and wrong, and blessed thistle is a common name that has been used for Silybum marianum. The species that more correctly is called blessed thistle is Cnicus benedictus.

With respect to the etymology of plant names, I use a variety of sources. Stearn (Stearn's Dictionary of Plant Names for Gardeners, Cassell, 1996) is usually my first choice, but others are often useful, as well. In particular, I often use the Dictionary of Word Roots and Combining Forms by Donald J. Borror (Mayfield Publishing, Mountainview California, USA, 1960) and Stearn's Botanical Latin (David & Charles Publishers; 4th edition, 1993). Another extremely useful reference is the (Royal Botanic Gardens) Kew publication, Three-Language List of Botanical Name Components by A. Radcliffe-Smith (1998). The reference to the Sierra Morena I found in The Names of Plants (Cambridge University Press; 2nd ed, 1989) by D. Gledhill. The epithet marianus -a -um evidently refers to St. Mary (of St. Mary; that is to say, not refering to any of the numerous saints of that name) and, as Michael points out, the state of Maryland.

It is of course plausible that the author of this combination, Joseph Gaertner (1732-1791), was a religious man who wanted to commemorate the Virgin Mary; however, I believe he would have used the epithet mariae, as the -anus ending in marianus denotes geography.

As I am clearly not a Latin scholar, I could easily be wrong. For example, I note that in A Gardener's Handbook of Plant Names (Dover Publications, New York, 1997) the author A.W. Smith makes reference to marianus being [the] "Specific name of various plants with white-mottled leaves, notably Our Lady's or blessed thistle (Silybum marianum). I am somewhat bothered by this, however, as an admittedly cursory search yielded no other plants with similarly white-mottled leaves with the epithet marianus, mariana or marianum. As I say, I'm not an expert and I'm happy to be proven otherwise, but I suspect that Smith is the source of this (probably erroneous) reference.

I want to say a word about the name "silybum marianum", although I'm not -by far- an expert, I speak only as an "aficionado".
It sounds quite strange to me that the name could refer to Sierra Morena, because "ma..." is different from "mo...".
"Morena" means dark-skinned, or tanned, it could be -i'm only guessing- that the name refers to the dark appearance of these mountains, located between Andalucía and Castilla. But, also, it could refer to the "moros", people from north Africa who have lived for centuries in Andalucía (Al-Andalus). Even nowadays, a common name for musulman people coming mainly from Morocco, here in Spain, is "moros".
That's why I believe that "marianum" has nothing to do with "morena".
By the way, I took the photos in Castilla, province of Toledo, near Aranjuez (more precisely, 40° 4'17.70"N 3°30'6.81"W). These plants are very common in central Spain.
I'm very glad to see my photos hear!!!

I think the general consensus in botanical Latin is the emphasis is on the penultimate syllable, hence, Sil-I-bum. I don't think this word would be an exception. Of course I've gotten into mild arguments with people over how to pronounce botanical names, but I just keep showing them botanical Latin books which support my argument.

On another note, as a naturopathic physician and herbalist who uses and recommends a lot of milk thistle seeds, all I can say is they are very nutritious for humans with no cases of nitrate poisoning every encountered yet.

This weed has taken the shape of widespread and invasive weed in NWFP, Pakistan. My experiments showed that it can cause 30-40% yield losses in wheat. However the yield losses and Silybum growth is rainfall and moisture dependent. At higher rainfall it can cause 100% yield losses.

This plant appears to be a thistle we here in Idaho, USA call the Canadian Thistle because it traveled from Cananda to the USA. I have read that the ripened seeds are the medicinal portion of the plant but have found no information on how the plant or it's parts might be prepared for use. Any information regarding the preparation and confirmation that my local "weed" is the Blessed one would be appreciated. Thank you.

K. Summa - Canadian thistle is Cirsium arvense.