Achillea — 12 species

Achillea, commonly known as yarrow, is a drought-tolerant perennial herb native to temperate regions of Europe and Asia, producing flat-topped flower clusters in shades of white, yellow, pink, and red over feathery, aromatic foliage. It thrives in full sun and lean, well-drained soil, requiring watering only when rainfall drops below an inch per week. All Achillea species are toxic to cats and dogs; the ASPCA confirms that yarrow contains glycoalkaloids and sesquiterpene lactones that can cause vomiting, diarrhea, drooling, and dermatitis.