In my early years of plant identification, using only a few inadequate plant guides, I was overjoyed to find a huge patch of “Wild Comfrey” nearby. Rabbits had eaten all but one of the Russian Comfrey plants I’d planted so I thought of it as a reprieve. I didn’t have the preferred comfrey, but I still had comfrey. Or so I believed.
My Peterson’s Guide to Medicinal Plants differentiated between Hound’s Tongue and Wild Comfrey. So I set out to learn how to tell them apart, after all, I didn’t want to make the mistake of using Hound’s Tongue! They look so similar! Similar by botanical name, too, (a clue that went over my head); Hound’s Tongue is Cynoglossum officinale, Wild Comfrey is Cynoglossum virginianum. Comfrey, on the other hand, is Symphytum officinale. These clues simply added to my confusion. How does Wild Comfrey compare to Comfrey? I was on a mission to locate the variety that had the least amount of potentially liver-toxic pyrrolizidine alkaloids (PA’s).
Meanwhile, I propagated my last remaining Russian Comfrey plant into a rabbit-protected stand and used it exclusively until I could figure out the true nature of Wild Comfrey. Which turned out to be; Hound’s Tongue. Wild Comfrey is Hound’s Tongue! Its not comfrey at all. But that’s not the end of the story.
It turns out that many herbalists still confuse Wild Comfrey with true comfrey, collecting and using it according to the medicinal properties of Symphytum. It looks very similar to comfrey, take a look at the photos above, notice the difference in the flowers. For an excellent close up series of photos of Hound’s Tongue, see this Missouri Plant site The flowers of Wild Comfrey (C. virginianum) are blue whereas the flowers of Hound’s Tongue (C. officinale) are more reddish-purple (not shown).
During the early 19th century herbalists believed it could serve as a substitute for comfrey and that appears to be the beginning of the mix up. Was this based on appearances alone, or because it actually did the job? Most contemporary herbalists dismiss Hound’s Tongue altogether as worthless and certainly, no match for comfrey. But if its worthless, why did the European settlers bring it with them to grow? Some modern books describe C. officinale as a European weed that crossed over and spread throughout N. America. But there are other references showing that the European variety, Cynoglossum officinale, was valued in its own right by herbalists who knew very well it wasn’t comfrey. Ancient herbalists used it and called it Hound’s Tongue because it was effective in quelling the annoying, non-stop bark of dogs!
Do you sense, as I do, that we’re reaching into the shadows of lost plant knowledge? Try to find information on Hound’s Tongue and you’ll discover very little. I’ll share what I’ve found below, but please, if you can add to this attempt at understanding Hound’s Tongue/Wild Comfrey, share what you know in the comments section.
A good starting place is to connect it to its plant family, Boraginaceae the Borage family. Members of this family are hairy and are used primarily as astringent wound healers when tissues need tightening up. It turns out that true comfrey, Symphytum, is also a member of the borage family! In many, but not all, cases — members of the same family can substitute for each other. So we have our first real clue that a valid relationship between Wild Comfrey and Comfrey may exist.
You’ll know you’ve found Hound’s Tongue by its sticky flat seed heads — known as beggar’s ticks– sticking to your clothes..The plant and root of Hound’s Tongue contains both astringent and demulcent properties. It also contains allantoin. This is the “magical” wound healer comfrey is known for.
Allantoin is prized for its ability to stimulate the growth of healthy tissue, help the skin to slough off dead or damaged cells and it protects the skin from further damage from various irritants. Now that we’ve found one valid reason why Hound’s Tongue/Wild Comfrey was used as a comfrey substitute, I should add that there are other substitutes. Plantain contains allantoin and so does another member of the Borage family, lungwort. If you want to use allantoin internally, skip the Hound’s Tongue/Wild Comfrey and go for plantain or lungwort…here’s why…
The borage family is known to contain pyrralizidine alkaloids. One isolated 14 different PAs from various parts of C. officinale. Apparently plants produce PAs as a chemical protection against herbivores and the most valuable parts of the plants (the young leaves) contain the highest concentrations. The youngest leaves of C. officinale (in the rosette) contain from 50-190 times higher levels than the older leaves. So, if you decide to harvest this plant for internal use, against the following warning, take the oldest leaves to reduce exposure to these toxic alkaloids. For readers who don’t know about PAs, they are associated with liver damage and are controversial. I generally avoid them for internal use – to stay on the safe side. My research indicates that PAs are higher in Hound’s Tongue & Wild Comfrey, than in true comfrey. Lungwort and plantain are PA-free.
So far, we’ve established Wild Comfrey as a useful external agent for wound healing, much like comfrey. What else does it do?
At this point we’ll have to turn towards ethnobotanical studies of how various North American tribes used Wild Comfrey. So far, my research indicates that C. virginianum was native to North American and it, rather than the European variety, is the one called Wild Comfrey. I wonder why? The purplish flowers of Hound’s Tongue, C. officinale, look more like comfrey. Maybe because the European variety was already too well known as Hound’s Tongue?
Wild Comfrey was used for the following:
Poulticed externally for burns and taken internally for sore throat
Tea made from the roots was used for cancer, genital itch, and gonorrhea
The Cherokee used a root tea for itching and a root syrup for cloudy urine
It was used in Green Corn Medicine
A formula included it along with other plants and fruits to improve memory
Used as a demulcent and sedative for coughs, catarrh, spitting of blood
Dysentery and diarrhea
Smoked like tobacco
Used externally for goiter, scrofulous tumors and ulcers
Anti-inflammatory and pain killer
While I’m cautious about internal use of PA containing plants, in the case of Hound’s Tongue/Wild Comfrey, I’m even more cautious than usual. The Physician’s Desk Reference for Herbal Medicine has this to say, “ Warning: The traditional folk medicinal preparations should not be used. Because of its high pyrrolizidine alkaloid content with 1,2-unsaturated necine parent substances, the drug is both hepatoxic and hepatocarcinogenic in effect. The drug should under no circumstances be taken internally.” Note that there are different kinds of PAs…saturated and unsaturated. Some are worse than others. Its my understanding that Wild Comfrey is ok for external, not ok for internal.
Do you have Wild Comfrey growing in your area? Some of the plant databases I looked at indicated it was listed as “at risk” , others called it an invasive weed. Generally it’s found in open woods from Connecticut to Illinois, southwards. Here in the N.W. Arkansas’ Ozarks we have quite a bit of it.
Its perennial with blue or pale-lilac flowers, the upper stem doesn’t have many leaves. Most of the heart-shaped leaves are lower down and clasping at their base. It flowers May-June and leaves are harvested during bloom. Roots are harvested in the fall. The herb can be dried and powdered. To make a poultice, just add enough water to the powder to make a paste. Allantoin is slightly soluble in water and hydroethanoles. To extract the allantoin into an oil requires use of an emulsifier (such as found in plant saponins).
So we have some limited historical and botanical information. As for studies, zip, nada. I looked for it in Dr. James Duke’s famous herbal database and its not there. I’ve been asking herbalists if they use it, how they use it, what kind of results do they get. So far, only a few local herbalists report satisfying results in using it externally for bruises, sores, itching painful skin and wound healing. I’ve also found some herbalists using it internally, thinking it carries the same low risk as comfrey PAs in short-term use. Most herbalists don’t seem to know about it. I hope this article will generate some interest, and some “asking around” with the result that we collectively recover the lost knowledge of Hound’s Tongue/Wild Comfrey. Is it worthless? A weed? Dangerous? Or another good addition to our medicine chest? And just how did it silence those pesky dogs?
References: (Note, I’ve looked through many reference books and its not in them so they aren’t listed).
Botany in a Day by Thomas Elpel
Herbal Constituents: Foundations of Phytochemistry by Lisa Ganora
Newcomb’s Wildflower Guide by Lawrence Newcomb
Physician’s Desk Reference for Herbal Medicine, Fourth Edition from Thompson