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In science, beauty. In beauty, science. Daily.

Silybum marianum

Silybum marianum
Silybum marianum

Thank you to -Merce-@Flickr for today's photographs (original image 1 and original image 2 via the BPotD Flickr Group Pool). Thank you -Merce-!

Michael Charters from Calflora.net explains that the pronunciation of the generic name for this plant has an emphasis on the first syllable, so it is said “SIL-i-bum”. However, that doesn't prevent certain coworkers of mine from repeating the humorous version of the name when they encounter the plant or images of such (I expect today's “word of the day” at work will be “sillybum”).

Humour aside for the moment, blessed milkthistle is a plant native to the Mediterranean area. Where agriculture has gone, though, it has followed, and it is now found in mild temperate areas around the globe. If you can't take the time to read this report on Silybum marianum from the Global Invasive Species Initiative, I'll share two facts that leapt out at me.

One is that seed production of this plant in infested areas can reach and exceed 500kg/ha (or 446 lbs/acre) – a massive amount, and an indication of why this plant can become a problem.

I'll quote the second fact from the site: “...One reason control methods have been sought after is due to the toxic potential of the thistle. Silybum marianum has caused some of the worst cases of stock poisoning in northwest Tasmania. The poisonous principle is nitrate (Macadam 1966). Cattle and sheep eat the plant material which contains potassium nitrate and break it down by means of ruminal bacteria into the poisonous form (Knott 1971). ‘The nitrite ion...combines with haemoglobin to form methaeglobin ...[which is] incapable of combining with oxygen. If large amounts of methaeglobin are present in the blood stream, affected animals will begin to show respiratory distress for lack of oxygen.’ (Knott 1971) Poisoning threats are increased when the plants are wilting after being cut or partly turned under during plowing and in wet weather (or) when soil moisture is high. In dry conditions they are not considered dangerous (Parsons 1973).” (references to further reading on the bottom of the essay on Silybum marianum).

Photography resource link: When Pretty Isn't Enough, the latest essay from Michael Reichmann of The Luminous Landscape, reminds that photographs are a synthesis of the observer and the observed.

16 Comments

Joann commented:

Is there anything good or beneficial about this plant?

Daniel Mosquin commented:

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.

Douglas Justice commented:

"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.

Michael Charters commented:

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.

PTowler commented:

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!

Michael Charters commented:

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.

Douglas Justice commented:

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.

Merce commented:

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!!!

Eric Yarnell commented:

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.

Azim commented:

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.

K. Summa commented:

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.

Daniel Mosquin commented:

K. Summa - Canadian thistle is Cirsium arvense.

Danielle commented:

The Silybum marianum ( milk thistle ) has been "toxic" to me like hell. I wanted to lower my cholesterol levels, and fatty liver ( fat spots on liver)and after taking only one capsule ( 250mg)I was sick as dog.I would not recomend this herb to anyone. Nausea, bloating, diarhoea, headache, even dizzines and sweating, panick attack, started 3 hours after ingestion, and lasted 24 hours.
I didnt die because I went on internet to read about this rubbish. Thank God I did, and I helped myself with drinking plenty of water ( with lemon to stop nausea) and 2 buscopan pills ( 4 times in 24 hours ) to stop upper abdo cramping. Warning to all not to take any herbal pills unless you are prepared to suffer bad side effects.

David Hollombe commented:

Carduus Marianus of Valerius Cordus
Carduus Mariae of Tragus, Fuchs, Gesner and Castore Durante
all sixteenth century

sergio aguirre commented:

This plant has a lot propeties as a tea, to deal liber diseases.

Dave Addison commented:

The stuff makes me feel sick as a dog also .
Because i have had Hep C for many a year this herb is always recommended and given enough time I always forget what a rotten effect it has on me and foolishly try it again.

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