Widespread throughout Britain, Heath milkwort (Polygala serpyllifolia) is a low-growing perennial which is usually found on grasslands and heath, but not on chalky soil or sand dunes where its close relative, Common milkwort, is more likely to thrive. The flowering season is from June to August and sometimes later;   the tiny flowers measure less than half an inch across, but at close range they are really beautiful.  Heath milkwort has a surprisingly wide colour spectrum which includes deep blue through to pale pink and white, and sometimes all these shades can be found growing close together. All these examples were photographed in the grass verges around our home in…