I spent most of the day identifying yesterday's specimens and entering all the data, so only took a couple of photographs of one of the rarer species that we found, Smooth Rupturewort - a rather undistinguished species more easily identified when in fruit.
This species is an annual or short-lived perennial of compacted sandy or gravelly soils, often with chalk or limestone fragments. Its habitats are generally kept open by seasonal standing water or other disturbance, and include forestry rides, golf courses, car parks, disused gravel-pits and disturbed areas in short grassland. It's most frequent in eastern England. Although it's quite rare as a native species, it's also grown as a garden plant, providing useful ground cover, and some of its occurrences are probably garden escapes.
As the name suggests, it has been used medicinally. Rupturewort contains herniarin and chemicals that may help stop spasms and help with eliminating excess water from the body. It has an anti-spasmodic effect on the bladder and is traditionally used to treat urinary tract infections (UTI), cystitis and kidney stones. A poultice may be made from the whole plant and used externally for healing ulcers. The whole plant is astringent, diuretic and expectorant and should be gathered when in flower. It has also been used for lung disorders, nerve pain, gout, arthritis, fluid retention, muscle and joint pain and for ‘purifying the blood.’ An aqueous extract is made from the plant and used as a hand cleanser.