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.
This plant may be found by the roadside, often near gardens, on railway banks, by river sides, in hedgerows, and in pastures and meadows, but it is not a common plant. The rootstock is spindle-shaped. The plant has no underground stems, and a straggling habit. The leaves are kidney-shaped, with 5-6 blunt divisions, divided into three nearly to the base, with hairy teeth. The deeply-notched purple petals are twice as long as the sepals, and the flower is 1/2 in. across. It is 1-3 ft. high. The flowers open in June and may be found onward till August. It is perennial (as another Latin name denotes).