One day, I was out foraging for wildflowers and came across the unique blue-tinged beauty above. I took a picture of it, but for the longest time couldn’t find anyone who could identify it. Several weeks later, the indigenous herb seller at the local tianguis (flea market) had a basket of these flowers dried. Delighted, I asked what the name of it was and what it was used for. He gave me the name “yerba de sapo” and with that, I was off on my investigations.
Yerba de sapo translates as toad’s herb in English. The particular variety I encountered is Eryngium carlinae but there are more than 200 varieties in this species around the world. Some sources say this plant is blue thistle, others record it as button snakeroot or sea holly, and yet another source lists it name as Eryngo.
The name in Spanish isn’t any less confusing. Yerba de sapo can also be spelled hierba de sapo, however, this is also the term used for Eryngium heterophyllum, another variety of the Eryngium genus with similar health uses. Other names include cabezona and cardón.
It has been used since the time of the Aztecs as a restorative tonic, remedy for kidney problems, and weight loss aid. The mashed leaves were used to make a poultice for sore eyes. It was also used to regulate menstruation.
For kidney ailments, a handful of yerba de sapo is boiled in a quart of water. Then one small glass is taken before breakfast. The herb guy recommended a handful of the herb should be boiled along with a bit of palo de brasil (Haematoxylum brasiletto) and palo azul (Eysenhardtia texana) in a tea drunk daily, to lower cholesterol levels and reduce weight.
A tea made from just the leaves is used to treat cough and whooping cough. The roots are edible and sometimes eaten toasted for urinary tract infections. The juiced roots are prescribed as an aphrodisiac, to improve urinary function or induce contractions. Combined with other herbs, it is used in a gonorrhea treatment. It is also used to treat kidney stones and as a cancer remedy. Yerba de sapo is often prescribed to allieviate angina pain and reduce arteriosclerosis.
Few scientific studies have been done on eryngium carlinae. However, those that have been conducted show promising results for its medicinal use. It has been shown to be effective in the treatment of diabetes. It has a hypocholesterolemic effect, meaning that yes indeed, it will lower your cholesterol. It reduces lipid peroxidation in the brain, kidney, and liver while increasing the catalase activity having antioxidant properties. It is antibacterial and has been approved as a beverage with renoprotective effects, thus good for the kidneys.
Eryngium carlinae grows in chalky or limestone soil and higher elevations. In fact, the specimen I came across during my foraging trip was in the mountains near El Cerro de Los Amoles in what had been a limestone evacuation area. The plant does not like to be moved, but it can be propagated with root cuttings.
Because it can stimulate uterine contractions, yerba de sapo should never be taken during pregnancy. It should not be ingested for more than eight weeks so as not to cause kidney damage. Those that are allergic to fennel, dill, or celery may experience an allergic reaction.