Microscopy studies of flower structures

The flowers of broad-leaved plants have four floral structures which differ significantly in shape from flower to flower. The sepals, petals, stigmas and pistils all have characteristic shapes and examples of all of them have been studied with scanning electron microscopy (SEM). The petals appear to be the most delicate of these structures and are therefore useful as indicators for senescence, as indicators for pollution effects or for developmental characteristics. Petals of most flowers are stamens which have switched roles during evolution from sexual organ to agents which attract pollinators. Even though they appear to be smooth to the unaided eye, they have fine sculptured detail when observed with SEM. Adaxial surfaces of some petals have closely packed cells which project from the surface and often have fine ridges or points. The reason for this is unknown, but is likely related to the reflection of light from petals.