any of several flowering plants, including the Texas bluebonnet (Lupinus subcarnosus), a North American annual plant of the pea family (Fabaceae), native to the plains of Texas. It grows about 0.3 m (1 foot) tall, has silky-haired leaves composed of five leaflets, and bears clusters of purplish-blue flowers that are marked in the centre with white or yellow. In the spring the plants cover immense areas in southern and western Texas like a blue carpet. The bluebonnet is one of the most popular wildflowers of Texas.

In Scotland the name bluebonnet is given to the bluebottle (Centaurea cyanus) and also to the blue scabious, or devil's bit (Succisa pratensis).