Bunches of developing fruits on common ivy, Hedera helix. The picture shows an ivy plant in December in Norfolk, UK. Visible are many former flower heads, each of which terminates in an umbel of ripening fruits (warm black berries) hanging below groups of umbellate flowers that have failed to produce berries (yellow-brown stalks, terminating in small yellow masses, the unfertilised flowers). Ivy flowers have exposed nectar, and attract a variety of late summer insect pollinators, including butterflies, craneflies and wasps. The terminal umbel reaches maturity and flowers before the other umbels in the panicle (here unfertilised). The picture illustrates the dependence of pollination on the weather. As the first flowers opened, it had been calm with daytimes highs of 18C. A week later, daytime highs averaged 12C with a fresh NE wind, grounding potential pollinators.