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 cornfields, fields, cultivated ground. The habit is erect, branched from the base. The stem secretes a milky juice, possibly a protection to the plant. The plant is smooth. The branches are erect and rigid, or prostrate. The leaves are broader above the base, or below the middle, linear, acute. The bracts are lance-shaped, toothed at the base. The flowerheads are forked, in rays of 3-5, the involucres small, nearly stalkless, the lobes rounded, with 2 horns. The small capsule has rough and warted angles, smooth. The seeds are pale-grey, 3-angled, keeled, wrinkled. The plant is 4-9 in. in height. It flowers from July to October, and is a herbaceous annual.