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 is found in gardens, and as an escape in corners where garden rubbish has been thrown out, near the seashore, and by roadsides, or generally in waste places. The habit is erect, being that of an undershrub below. The leaves are pinnate, divided, bluish-green, the segments entire, linear, acute, wavy. The flowers are white, with 6 sepals, which are linear to lance-shaped, divided, nearly equal, 3-fid, the sepals being of the same number, the stalks not so long as the latter. The fruit is oblong, wrinkled. There are 4 stigmas as a rule. The seeds are kidney-shaped, rough. The plant is 1-2 ft. high, flowering in July and August, and is a herbaceous biennial.