Rhinanthus serotinus, commonly known as Late-Flowering Yellow Rattle, is an annual herb native to a variety of grassland habitats, including meadows, pastures, and open woodlands across Europe and Western Asia. It typically grows to a height of 0.5-1.5 feet (0.15-0.5 meters) and is characterized by its toothed leaves and tubular yellow flowers with a distinctive inflated calyx, which rattle when the seeds mature, hence the common name. The flowers, which bloom in the summer, are showy and attract pollinators such as bees.

Late-Flowering Yellow Rattle is valued for its ability to parasitize the roots of grasses, thereby reducing the vigor of the grass and allowing a greater diversity of wildflowers to flourish. This makes it beneficial for creating and maintaining traditional hay meadows and wildflower gardens. It is often used in grassland restoration projects to suppress grass growth and increase biodiversity. This plant prefers full sun to part shade and thrives in medium draining clay or loam soils. It requires medium amounts of water and is relatively low maintenance once established. However, it can be difficult to establish in well-established grassy areas without initial soil disturbance.CC BY-SA 4.0