When the flowers of yellow-rattle fade, the brown calyxes (containing the sepals) in which the tiny seeds ripen can be seen and heard - they give a distinctive 'rattle', hence the common name. Yellow-rattle is an annual that thrives in grasslands, living a semi-parasitic life by feeding off the nutrients in the roots of nearby grasses. For this reason, it was once seen as an indicator of poor grassland by farmers, but is now often used to turn improved grassland back to meadow - by feeding off the vigorous grasses, it eventually allows more delicate, traditional species to push their way through.
How to identify
Yellow-rattle has yellow, tube-like flowers protruding from an inflated, green calyx, which appear May to September. It has serrated leaves with heavy, dark veins, which sprout opposite each other all the way up the stem. Its stems have black spots.
Did you know?
Yellow-rattle is the foodplant for the larvae of two rare moths, including the grass rivulet.
