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 species is waste places as well as walls. The radical leaves are ovate, entire. The stem-leaves are deeply divided nearly to the base. The flowers are white or purple, with a very short spur. The plant is 6-9 in. in height, and is an annual.