Meadowsweet (Filipendula ulmaria (L.). All plants contain some traces of salicylates, the natural form of aspirin, but several are especially good sources of these compounds. It is one of the better ones. That's why it has long been used to fight colds, flu, fever, arthritis, and muscle aches and pains. Meadowsweet contains an aspirin-type compound called salicylic acid. It has anti-septic, anti-ulcer, anti-inflammatory and diuretic properties. Meadowsweet is used to treat rheumatism, ulcers, diarrhea, kidney problems and gastric acidity.