This section is from the book "British Wild Flowers - In Their Natural Haunts Vol5-6", by A. R. Horwood. Also available from Amazon: A British Wild Flowers In Their Natural Haunts.
The habitat of this plant is boggy places, moist heaths, swamp)' heaths, the sides of ditches. The habit of the plant is erect. The stems are slender, sometimes much-branched. The lower leaves are broadly ovate, the intermediate leaves ovate to lance-shaped, the base heart-shaped. The upper leaves are lance-shaped, rounded below, entire, somewhat scalloped below. The leaves are shortly-stalked or stalkless, and burnt. The flowers are in the axils, opposite, turned one way. They are pale-pink in colour. The calyx is downy. The tube of the corolla is straight, and the corolla is small. The nutlets are smooth. The plant is 4-12 in. in height, flowering between July and October. It is a herbaceous perennial.