Humidity, nectar and insect visits to flowers, with special reference to Crataegus, Tilia and Echium

Heliotropic flowers (Dryas integrifolia, Papaver radicatum) act, in sunshine, as solar reflectors, their corollas focusing heat on the sporophylls. Considerable intrafloral temperatures are generated. Winds above 3.8 meters per second and cloud abolish the effect. Insects that bask in the flowers also gain heat. The phenomena areimportant in maximizing the small heat budget.