As the weather turns colder in some parts of the world, signs of autumn begin to appear. The leaves of some trees turn bright shades of red, yellow and orange. At this time of the year, depending on your location, you may also see a familiar flower: chrysanthemums. We often call them “mums” for short. In parts of the United States, many people use chrysanthemums as decorations. The flowers sit next to pumpkins for Halloween, October’s famous holiday. But then the mums are thrown away along with rotting jack o’ lanterns. This yearly tradition bothered plant expert Jessica Damiano. In a recent article for the Associated Press, she wanted to know why people simply threw away their mums. So, she asked some of her neighbors in Long Island, New York. Everyone had the same answer: They thought the flowers were annuals -- flowers that only last for one season. Damiano explained that there are annual and perennial mums. Perennials come back for several growing seasons. Garden chrysanthemums, she adds, are actually perennials. Annual chrysanthemums are often sold in stores as potted gift plants. Special plant stores usually sell perennial mums.