Hogweed (Heracleum sphondylium) flowerhead seen from below to show the umbels and umbellules. These plant structures are common to all but a few of the Apiaceae (celery family, formerly Umbelliferae). The umbels radiate from the top of a stem and at the tip of each umbel radiate the umbellules (secondary umbels) on which the flowers are formed. The arrangement can vary from being flat topped to almost spherical. The term "umbel" was coined in the 16th century from the Latin for a sunshade or umbrella. Photographed in Worcestershire, UK.