The term 'yellow-flowered medicinal plant' can be summarized by two crossword solutions: Arnica (6 letters) and SENNA (5 letters). Arnica is a genus of perennial, herbaceous plants in the sunflower family, native to mountainous regions of Europe and North America. It has been used for centuries as a medicinal herb to reduce inflammation and pain. SENNA is a large genus of flowering plants in the legume family, native to tropical and subtropical regions of the world. It has been used for centuries in traditional medicine to treat constipation and other digestive issues.