Pharmacognosy is the study of medicine from natural sources like plants, animals, fungi and minerals. The document discusses four plants: sweet violet, liquorice, rose, and their traditional uses. Sweet violet contains anti-inflammatory compounds and has been used to treat cough, influenza, pneumonia and reduce swelling. Liquorice contains glycyrrhizin and is used as a demulcent, expectorant and to treat ulcers and sore throat. Rose contains essential oils and is used as a tonic for vital organs and to treat conditions like hepatitis, constipation and eye inflammation. Traditional herbal medicines are described as treatments for various ailments.