This section is from the book "Botanic Drugs Their Materia Medica, Pharmacology and Therapeutics", by Thomas S. Blair. Also available from Amazon: Botanic Drugs, Their Materia Medica, Pharmacology and Therapeutics.
Water Eryngo, Button Snakeroot, Eryngium yuccaefolium. Emetic in large doses; diaphoretic, diuretic, and expectorant in smaller doses. Used principally in chronic genito-urinary disorders. Dose of fl., 10 to 30 minims.
In old cases of gleet or cystitis, eryngium may be used. So many patients have deranged digestion from long taking of more potent agents for these disorders that eryngium is a useful drug to substitute for them, since moderate dosage is not apt to disagree with the stomach. In general, eryngium may not be classed as of much value.