Several species of hawthorn or mayflower are used to provide a remedy that is a firm favourite among practitioners for anxiety related heart problems, symptoms associated wtih atherosclerosis ("hardening of the arteries"), and hypertension (high blood pressure). Substantial evidence from clinical trials shows that proprietary hawthorn extracts (standardised either to oligomeric procyanidins or to flavonoid content) can help improve the pumping ability of the heart in cases of mild to moderate heart failure. The evidence base for other uses is disappointing. However, the apparent cardioactive properties beg the question of how hawthorn works, and although most of the research in this area has looked only at isolated hawthorn constituents in a laboratory setting, there is enough to suggest important effects on heart muscle, coronary circulation, and blood vessel function. This is a remedy that holds promise for future research.