The herb this week is an oddity. It isn’t found in many formulas, and I have never seen it used in the school clinic medicinary. Why review it? I did a paper on it last year because it’s something I see around me frequently here in Oregon and I always wondered whether it was medicinal. I thought I would share my findings and add to them – I’d love to hear from anyone who has used this herb in their practice or taken it as a patient. What experience did you have of this odd plant?
Mù Zéi is a member of the family Equisetaceae, which is a very primitive plant form that was once quite dominant and even reached tree height about 200 million years ago. There are eight surviving members of the family, and none of them reach such great heights today. As a testament to their primitiveness, it is worth noting that Mù Zéi propagates primarily via spores. This fact often finds the family grouped with ferns, though they share few similarities other than their method of propagation.
The fact that there are eight members of this family, and all of them are referred to commonly with a huge number of seemingly interchangeable names made my research a little more difficult. I studied several books but could not find a true consensus concerning which species is the “true” Mù Zéi, and indeed, whether there were medicinal differences between the species.
However, according to my main online reference, Plants for a Future, Western botanical usages vary with the species, I can only assume that the same is true of the Chinese usage. The species listed in Bensky as being standard Mù Zéi is Equisetum hiemale, which is also written as Equisetum hyemale.
Mù Zéi is a visually striking plant, as it has very clean lines and an unwavering growth habit. It is mostly deep green with tan or white joints at each level of new growth, often with a black band around the joint. Stems are tube shaped and hollow, but very rigid. At the top of the stem is a pinecone shaped structure where the spores grow. Most species enjoy marshy territory, and this is the environment one most often runs into common field horsetail that is prevalent in the United States. However, it can also be found on rocky hillsides, along roads and even in fairly dry plains. In many situations, Mù Zéi can be quite invasive, as they thrive in disturbed areas just as well as they do in carefully prepared soils.
Energetically the plant has a pure Wood phase quality that is actually quite delightful to encounter. One gets the feeling that nothing will get in the way of the plants growth and that it delights in growing. However, it is also a brutally efficient being – no fancy flowers or branching, not even any leaves! This gives it an almost alien quality – like something that doesn’t quite fit in to our world as it is today. In fact, if I were to associate a humanoid persona to Mù Zéi, I would probably pick Dr. Spock from the original Star Trek series! Using my other physical senses, I can tell you that the herb doesn’t have much of a smell or taste though when I smelled it I could certainly tell it had grown in a musty, damp environment. The taste is slightly bitter, perhaps, but nothing like Huang Lian. It is worth noting again the rigidity of the herb, even in dried form. This rigidity is created due to a high amount of silica in the herb, which makes it a plant you do not want to eat as the crystals can cause serious damage to soft tissue.
Names and Etymology
The first character of the herb name is Mù (木). Various sources indicate that this is a picture of a tree with a trunk, branches, and roots. The variety of English meanings spans from a tree / wood / timber / lumber to simple and honest. However, in this case it most likely refers to a tree, or simply wood.
The second character of the herb name is Zéi (Simplified: 贼 Complex/Traditional: 賊). The character has undergone some distortion to arrive at its modern form, where it appears to be composed of the radical for money and the radical for knife. My sources indicate that it was most likely originally composed of a phonetic radical and the radical for weapon. English meanings range from a thief or bandit to a traitor to clever, cunning or crafty.
Putting it together then, the most common meaning for the full word is wood traitor or tree thief. Apparently this name has something to do with the fact that the dried form was and can be used as sandpaper – thus it is a “traitor” to its “own kind” – a plant that grinds down plants! This herb also has many English common names, the most popular being Bottle Brush, Horsetail, Scouring Rush and Shavegrass.
From a Chinese herbalist standpoint, Mù Zéi falls into the category of Herbs that Release the Exterior. Interestingly, Mù Zéi does bear a resemblance to Ma Huang, the premier herb in this category. In fact, there is a species called MuZei Ma Huang! While often herbs in this category are thought of as being either warming or cooling, Mù Zéi is neutral. It is a sweet and bitter herb and enters the wood channels Liver and Gallbladder as well as the metal Lung channel.
Bensky’s materia medica lists its key characteristics as “disperses wind-heat in the exterior; specific for superficial visual obstruction.” One would use this herb when a wind-heat illness caused redness, itching, puffiness and general irritation of the Liver orifice, the eyes. However, MuZei is also used to stop bleeding, especially when blood is found in bowel movements whether from small bowel ulcers or hemorrhoids.
If we look briefly at the herb from a more symbolic standpoint, using the doctrine of signatures, confirmation for the above emerges. The color, green, easily relates it to the Wood element – and thus Liver and Gallbladder. The Lung association can be seen as relating to the tube shape of Mu Zei, herbal tubes often being compared to the tubes of the trachea, bronchi and bronchioles.
It is worth noting that the ancient Western herbalist Galen recommended that this herb be used in the treatment of urinary problems, a usage that continues in the modern Western tradition. This can also be seen as an expression of the tube shape of Mu Zei as similar to the urethra and other tubular structures in the exocrine system. The texture and density are, perhaps, a little more difficult to relate to the medicinal properties. Given that we use this herb primarily for dry and irritated eyes, it’s hard to see why such an abrasive plant would be used! Perhaps insofar that often the dry and irritated red eyes are seen as a manifestation of Liver/Gallbladder fire, the “wood traitor” can be used to “shave down” the overzealous Liver Qi. Also, returning to the Western tradition, Horsetail can be used in the treatment of Osteoperosis and other bone density problems – the strong and rigid texture of Mu Zei can be seen as related to the bones.
Again, please let me know in comments if you have further information about this herb – for whatever reason, it fascinates me!
About Eric Grey
Hi - I'm the founder of this site and the primary master of all functions here. When I'm not writing, you can find me reaching out to the Chinese Medicine community across the web and in my own backyard. I currently teach Chinese herbs at my alma mater, the National College of Natural Medicine. Additionally, I'm the founder of Watershed Wellness, a thriving local clinic in Southeast Portland in Oregon. No matter where I'm working, you'll find my focus on the Classical approach to Chinese medicine laced throughout everything I do.