Comfrey, Symphytum officinale – Weekly Weeder #40

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Today’s featured plant is Comfrey, Symphytum officinale.

Comfrey is also known as common comfrey, knitbone (knit-bone, knit bone), knitback, knit bond, Quaker comfrey, gum plant, bruisewort, blackwort, black root, slippery root, boneset, consound, healing herb, salsify, and wallwort. *Note: This should not be confused with salsify/oyster plant (Tragopogon porrifolius), a garden root vegetable, which is not related.

Range and Identification of Comfrey

Comfrey is native to Europe through Siberia. It has been introduced to North America and other temperate regions, and can be found throughout much of the U.S. and up into Canada (see map). It prefers moist soil, and is often found as a garden escapee. Russian comfrey (S.x uplandicum) is a hybrid between common comfrey and prickly or rough comfrey and prefers drier ground.

The comfrey plant is a perennial, blooming in the spring/summer and dying back in fall/winter. It has a dense, clumping habit and grows up to 3 feet in height. Flowering stalks have leaves attached in an alternating pattern up the stem.

Comfrey flowers are borne in clusters at the top of the stem. They are delicate and bell-shaped, with only a slight aroma. The blooms measure about 1/2 ” in length, and come in an assortment of colors including white, pink and blue. The plant looks somewhat similar to foxglove, but foxglove flowers are larger and more showy.

Comfrey leaves are lance shaped, and may reach up to 1 1/2 feet in length. Like borage, the leaves are hairy and rough. (Comfrey is in the borage family.)  As you can see, the veining is quite pronounced. On the leaf stem, there are small green wings that flair out on either side of the stem.

Comfrey roots have a branching habit, forming dense clusters and making them difficult to remove. They are brittle and break easily, and a new plant will regrow from the leftover bits. (Don't plant them in a spot unless you're sure you want them there.)  The roots are dark brown on the outside and white on the inside and measure less than 1/2 inch in diameter.

Comfrey as Wildlife Habitat

Illinois Wildflowers list the faunal associations of comfrey:

For North America, little is known about floral-faunal relationships for this plant. According to Müller (1873/1883) in Germany, nectar-seeking long-tongued bees are the primary pollinators of the flowers, particularly bumblebees and Anthophorine bees (Anthophora spp.); sometimes bumblebees steal nectar by chewing holes near the corolla bases of the flowers. Müller also reported that honeybees, Halictid bees, and Syrphid flies (Rhingia sp.) would also steal nectar from the corolla holes that were created by bumblebees. Common Comfrey is somewhat toxic to mammalian herbivores and humans because it contains pyrrolizidine alkaloids. Over a period of time, these alkaloids can cause irreversible liver damage if the foliage and especially the roots are consumed in sufficient quantity. Horses, cattle, goats, and pigs are susceptible to being poisoned; apparently sheep are more resistant to adverse reactions.

Medicinal Uses of Comfrey

Comfrey contains pyrrolizidine alkaloids, which are naturally occurring plant toxins. As mentioned in the wildlife section, if consumed in large amounts, these can be toxic to the liver. There is a very detailed discussion of potential comfrey toxicity on the GardenWeb forums, in which the author states that based on available data, a human would need to consume nearly their weight in comfrey leaves to cause death. Clearly, this is not an issue under normal circumstances.

The leaves of comfrey have a much lower concentration of the toxins than the roots (almost none at certain times of the year) and are considered safer for internal use (comfrey root is no longer recommended by many herbalists for internal use). Backyard Medicine suggests that comfrey tea should not be used for more than six weeks at a time. It should also not be used if you are pregnant or nursing, or given to young children. *Note:  Russian comfrey has higher pyrrolizidine alkaloid levels than common comfrey.

As its many folk names suggest, comfrey is one of the best herbs for healing broken bones, sprains, strains, bruises and tears. You can consume 1 – 2 cups of comfrey tea per day until the damage heals.

To make a fresh comfrey poultice to apply topically,  dig up comfrey roots, clean and chop into short lengths. Blend with an equal amount of fresh comfrey leaf and just enough water to mix. Puree until relatively smooth. Apply to a piece of gauze and place over the affected body part and cover with breathable wrapping. Replace daily. (From Backyard Medicine.)  Learning Herbs makes a poultice using just the leaves combines with a bit of water, pureed, and mixed with enough flour to thicken. For my cut fingertip, I just smashed a leaf, combined it with some dried yarrow, and bandaged it on.

The leaves can also be dried and infused in olive oil, and this oil can be made into a salve. If you don't have comfrey available, you can purchase a variety of comfrey products from a reputable herbal provider like Napiers.

Comfrey may also be used to treat circulatory conditions such as varicose veins and spider veins. (Need to try some salve this summer and see if I can chase away my spiders!)  Backyard Medicine also suggest that it may be helpful for healing old wounds, such as surgical scars, and minor cuts.  It is not recommended for topical treatment of deep cuts or puncture wounds, as it may cause the would to close at the top before it heal underneath, increasing the risk of abscess/infection.

9/4/2013 – I had a chance to check out the healing properties of comfrey first hand when I sliced my fingertip open recently. The cut was about one inch long and 1/8 inch deep at the deepest. It bled like crazy, so I knew the wound had been flushed out. I made a compress of fresh comfrey leaves and dried yarrow, which is antibacterial and also known for treating wounds. I kept a comfrey compress on it for 24 hours, and kept it covered for another 24. The cut happened Monday night, and this is what the wound looks like on Wednesday morning. No scab, no scar, no pain – which is great, because I still have a lot of canning to do.

One of the active compounds in comfrey is allantoin. This anti-inflammatory chemical stimulates cell proliferation and supports the immune system. The plant also contains tannins, mucilage, gum, resin and volatile oil. The roots were commonly used for bronchitis and other chest complaints, and for stomach issues such as ulcers, but now other herbs are generally recommended. The Holistic Herbal discusses more of these other uses.

As always, any medical information is for informational purposes only. Always exercise caution when using any wild plants and make sure you have positively identified the plant.

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This post is written in collaboration with Napiers as part of the Weekly Weeder series.