It is a hemi-parasitic herbaceous annual plant that gains some of its nutrients from the roots of neighbouring plants. It grows to tall, with opposite, simple leaves, with a serrated margin. The flowers are yellow, produced on a terminal raceme. The fruit is a dry capsule, which contain loose, rattling seeds when ripe; the plant's name refers to these. Its preferred habitat is dry fields or meadows, where its flowering period is between June and September. The plant can associate with many different host species, notably Poaceae (grasses) and Fabaceae (legumes).