This section is from the book "Wayside And Woodland Blossoms", by Edward Step. Also available from Amazon: Wayside And Woodland Blossoms: A Guide To British Wild-Flowers.
A very neat and beautiful plant, not nearly so well-known as it should be. It is an annual plant, with erect stem, less than a foot in height, the leaves in pairs growing together at their bases, and funnel-shaped pink flowers produced in terminal cymes. It grows in woods and sandy or chalky pastures, flowering from June till September.
The name is from the Greek, Eruthros, red, in allusion to the pink flowers.