This section is from the book "British Wild Flowers - In Their Natural Haunts Vol2-4", by A. R. Horwood. Also available from Amazon: A British Wild Flowers In Their Natural Haunts.
Corn Gromwell is found in Europe, N. Africa, Siberia, W. Asia, as far as N.W. India, in the North Temperate Zone, and has been introduced into the United States. It is unknown in any early deposits. In Great Britain this plant does not grow in Glamorgan, Brecon, Radnor, Cardigan, in South Wales, Montgomery, Merioneth, the Isle of Man, Dumfries, Wigtown, Kirkcudbright, Peebles, Selkirk, S. Perth, the whole of West Highlands except Mid Ebudes, W. Ross, Sutherland, Caithness, Orkneys, Shetlands, but elsewhere from Ross to the south coast. It is native in Ireland.
Corn Gromwell is one of the plants which seldom, if ever, subsist anywhere else except in cultivated fields of one description or another, being found with other plants, such as Gold of Pleasure, Corn Cockle, Flax, etc, which are only found in cornfields or in waste places, when they may reasonably be supposed to have sprung from a like origin.
The first Latin name (from Greek) refers to the hard stony character of the nuts or fruit. Corn Gromwell is a slender-stemmed plant, erect, branched at the base, with narrowly elliptical, linear, tapering, hairy leaves, the radical leaves stalked, the stem-leaves stalkless, clasping, hairy, and the hairs are bulbous both sides.
The flowers are small, creamy-white, growing in short cymes, terminal, with long; leaf-like bracts. The calyx is equal to, or slightly shorter than, the corolla, lengthening in fruit, and spreading, containing 3 or 4 pale-brown, polished nutlets, which are covered with dots, and wrinkled.