Nothing makes the pollen-gathering bees happier than the flowering of our shrubby st. john's wort (Hypericum frondosum). You can see why one of the popular varieties is called 'sunburst'. Although the flower is only about 4 cm in diameter, the shrub produces masses of flowers at once for quite a buzzing display. As easily observed the stamens are numerous which is typical for this family, Clusiaceae, formerly Guttiferae. Given the number of stamens and the number of bees (at least 5 different ones) collecting pollen, how could the single pistil not get pollinated? If you google st. john's wort you'll get pages and pages advertising and discussing it as an herbal remedy for depression, but according to Quack Watch the best clincal trials have not found its effect to be significantly different from a placebo control. However this does not affect its sale as an herbal supplement or from its purveyors making false claims about its value. Better to enjoy the flowers and bees.