What is another name for milk thistle?

November 21, 2025 •

3 min read

Milk thistle, a plant celebrated for its health-promoting qualities, goes by several other names depending on the region and context. A common alternative is St. Mary's Thistle, which, like the primary name, is connected to a legend about the Virgin Mary.

Quick Summary

This article details the various common and scientific names for milk thistle, a flowering herb of the daisy family. It covers the botanical classification, folklore, and practical distinctions between similar-sounding plants.

Key Points

Botanical Name: The official scientific name for milk thistle is Silybum marianum.
Common Names: Other names include St. Mary's Thistle, Marian Thistle, and Blessed Milkthistle.
Identifying Feature: Milk thistle is easily recognized by its large, glossy leaves with distinctive white marbling.
Active Compound: The health benefits are largely attributed to the active compound, silymarin, which is extracted from its seeds.
Distinct from Others: It should not be confused with other plants like blessed thistle (Cnicus benedictus), which have different properties.
Traditional Uses: The herb has a long history of use for supporting liver and gallbladder function.

Silybum Marianum: The Scientific Name

Beyond its common monikers, the official scientific name for milk thistle is Silybum marianum. This binomial nomenclature is universally recognized in the fields of botany, herbal medicine, and scientific research. The genus, Silybum, refers to a species of thistle, while marianum is derived from the legend of the Virgin Mary. This formal name is particularly important for ensuring accuracy in clinical studies and for distinguishing it from other plants that share similar common names. For example, confusing milk thistle with 'blessed thistle' (Cnicus benedictus) can be problematic, as they are distinct plants with different properties and traditional uses.

Other Common Names for Milk Thistle

While Silybum marianum is the most precise term, several colloquial names are used worldwide. Some of the most prevalent include:

St. Mary's Thistle: This name is rooted in a legend where the Virgin Mary's milk is said to have fallen on the leaves of the plant, creating the white veins that are a distinguishing feature.
Marian Thistle: A direct variation of St. Mary's Thistle, also referencing the Virgin Mary.
Blessed Milkthistle: Another name derived from its historical associations with folklore and its use in traditional medicine.
Mediterranean Milk Thistle: This name points to the plant's native region, encompassing parts of Southern Europe and the Mediterranean.
Variegated Thistle: A descriptive name referring to the unique mottled or marbled pattern of its glossy green leaves with white veins.

How to Distinguish Milk Thistle from Lookalikes

Given the existence of several thistle species, it is important to correctly identify Silybum marianum. The distinctive white-marbled leaves are its most notable characteristic, but other details can help with identification. A comparison with other thistles helps highlight these differences:


Feature	Milk Thistle (Silybum marianum)	Blessed Thistle (Cnicus benedictus)	Canada Thistle (Cirsium arvense)
Leaves	Glossy, dark green with distinct white marbling.	Light green, hairy, and without prominent white veins.	Smaller, green, and have very sharp yellowish prickles.
Flowers	Large, typically purple or reddish-purple.	Smaller, yellow, and often bristly.	Smaller, purplish flowers in clusters.
Habit	Upright, biennial, and can grow quite tall.	Sprawling annual.	Aggressive perennial that spreads via rhizomes.
Flower Bracts	Large, with triangular, spine-edged appendages.	Spiny basal bracts.	Broadly triangular and less spiny than other thistles.
Primary Use	Liver and gallbladder support.	Stimulant for digestive juices and appetite.	Considered an invasive weed.

The Active Compound: Silymarin

The term silymarin is often used interchangeably with milk thistle, but it is actually the name of the active compound extracted from the plant's seeds. Silymarin is a complex of several flavonolignans, primarily including silybin, which is believed to be the most active component responsible for the herb's effects on the liver. When purchasing milk thistle supplements, you will often find them standardized to a certain percentage of silymarin to ensure potency. The concentration and quality of silymarin can vary significantly between different products.

Traditional and Modern Applications

Historically, various names for milk thistle have been used in traditional remedies for centuries. For example, Roman naturalist Pliny the Elder wrote about its use for liver-related issues. Today, its use in herbal medicine continues, largely focused on liver and gallbladder health. Some of the main applications include detoxification support and as a complementary therapy for conditions like nonalcoholic fatty liver disease (NAFLD). Its antioxidant and anti-inflammatory properties are also under study for other potential health benefits, such as blood sugar control and skin health.

Conclusion

In summary, while Silybum marianum is the definitive botanical name for milk thistle, it is widely known by common names such as St. Mary's Thistle, Marian Thistle, and Variegated Thistle. These names all refer to the same plant, which is valued for the active compound, silymarin, found in its seeds. Understanding these different names is crucial for distinguishing it from other plants and for accurately researching its traditional uses and potential health benefits. When seeking supplements, always check for the scientific name to ensure you are getting the correct herb. Its unique appearance, with white-marbled leaves and purple flowers, serves as a natural identifier, but cross-referencing with other features helps avoid confusion with similar-looking species. The plant's enduring reputation as a liver tonic and detox aid underscores its significance in both historical and modern herbal practices. For further scientific information, consider reviewing data from reliable sources like the National Center for Complementary and Integrative Health. NCCIH - Milk Thistle: Usefulness and Safety

Frequently Asked Questions

No, blessed thistle (Cnicus benedictus) and milk thistle (Silybum marianum) are different plants, though they both belong to the Asteraceae family. They have different appearances and are traditionally used for different purposes.

The name St. Mary's Thistle comes from an old legend. It is said that the Virgin Mary's milk fell onto the plant's leaves, leaving behind the distinctive white veins seen on the foliage today.

Silymarin is the name for a group of flavonoid compounds extracted from the seeds of the milk thistle plant. It is the main active ingredient and is responsible for the plant's antioxidant and liver-protective properties.

You can identify milk thistle by its unique, glossy, dark green leaves with striking white veins or marbling. The plant also produces large, reddish-purple flowers.

Milk thistle is native to the Mediterranean region of Europe, but it has since been introduced and naturalized in many other parts of the world, including North America.

Traditionally, milk thistle has been used for liver and gallbladder disorders. It is also known for its antioxidant and anti-inflammatory effects and is used for detox support and potentially improving skin health and blood sugar levels.

Some studies suggest milk thistle may help treat nonalcoholic fatty liver disease (NAFLD) by improving liver enzyme levels, but more research is needed. It is important to consult a doctor before using it for any medical condition.