Although Milfoil was originally a plant of damp or fresh meadows, nowadays it is also found in gardens, hedgerows, forest margins, and forest rides. It is a very adaptable plant and it was this attribute which, in the 1920s and 1930s, prompted American scientists to make use of Milfoil as the subject of a long-term research programme experimenting with the transplantation of plants.

Another small field species often growing in sandy and gravelly soils (but in warmer regions than Hop Trefoil) is Hare’s-foot Trefoil (T. arvense L.). It, too, requires light and is mostly found in stubble, although it also grows in sunny hedgerows even in quite acid soils. It is not generally present in limestone regions.

Yet there is a darker side to this very pretty flower. There was a time when farmers had to search their harvested wheat for its seeds, to separate the Corn Cockle from the grain. The reason for this very old practice of separating the wheat from the chaff is quite simply that Corn Cockle seed is highly toxic: an admixture of even five per cent in grain is dangerous. Flour turns bitter, causing diarrhoea in humans, and the seed is harmful, too, in animal feed, particularly in the case of young stock.

T. campestre is one of the few yellow species of the genus. It grows to a height of 10 -30 cm. The flowers are borne on erect stalks in heads of twenty to thirty flowers which turn brown when spent. The flowering period is from June until autumn for plants which have germinated in spring; or only in spring for plants which have germinated the previous autumn. This, then, is an annual or overwintering plant multiplying only by means of seeds.

As gardeners have never viewed Corn Cockle with the same distaste as farmers, it has survived in many places as a pretty garden annual flowering in June and August. Corn Cockle is now a cosmopolitan species, occurring across Europe and in Africa, Australia and North America (where it was introduced a century ago). With concentric rings of small tubercles, the seed measures 3-4 mm across and ripens throughout summer along with the grain.

Often the overwintering generation produces seeds early so that the offspring flower in the autumn of the same year. Tough and bitter to the taste, the plant is only tolerable as fodder for sheep.