Lorena found these in a bag at Lubin's store. 2 small bags for 10 pesos (4" by 4") . She made me a tea saying it made her grandmother feel better. To me it tasted like Alphalpha tea from the hippy days. I found one article that said it is a diuretic. No idea where it's from but at that price, it's not imported.
The plant contains several substances which can be used medicinally. It is rich in the minerals silicon (10%), potassium, and calcium. The buds are eaten as a vegetable in Japan and Korea in spring time. All other Equisetum species are toxic.
Fertile shoots, in late April.
In polluted conditions, it may synthesize nicotine. Externally it was traditionally used for chilblains and wounds. It was also once used to polish pewter and wood (gaining the name pewterwort) and to strengthen fingernails. It is also an abrasive. It was used by hurdy-gurdy players to dress the wheels of their instruments by removing resin build up.
Equisetum is used in biodynamic farming (preparation BD 508) in particular to reduce the effects of excessive water around plants (such as fungal growth). The high silica content of the plant reduces the impact of moisture.
E. arvense herb has been used in traditional Austrian medicine internally as tea, or externally as baths or compresses, for treatment of disorders of the skin, locomotor system, kidneys and urinary tract, rheumatism and gout