What type of plants are defined as perennials?

Perennials are defined as plants that grow and thrive for multiple years, consistently returning each growing season. This characteristic allows them to establish a root system and foliage that can survive through various environmental conditions. Unlike annuals, which complete their life cycle in one year, or biennials, which typically live for two years, perennials provide a long-term presence in landscapes and ecosystems. Their ability to regrow each year makes them valuable for gardeners and land management, as they can contribute to soil health and reduce erosion over time.

The other options reflect different life cycles of plants: annuals complete their cycle in a single year, while biennials take two years. The description of plants that "live for a single season" and those that "bloom only once" is also characteristic of other plant types and does not apply to perennials, which are known for their longevity and repeated growth.