How do cuckoopint flowers trap flies and use them for pollination?

The cuckoopint (Arum maculatum) employs a sophisticated pollination strategy that relies on trapping insects to ensure cross-pollination.

In the early evening, the plant releases a fetid odor and generates heat—triggered by the hormone calorigen—to attract minute flies. These insects enter the spathe through a zone of downward-pointing bristles, which act as a one-way trap, forcing the flies into a smooth-walled floral chamber from which they cannot escape.12

Once trapped, the flies feed on a nutritious secretion produced by female flowers at the base of the spadix. If the flies previously visited another cuckoopint, they deposit pollen on the stigmas. Later that night, as the female flowers become unreceptive, the male flowers higher on the spadix release a rain of pollen onto the insects. The following day, the bristles wilt, allowing the pollen-laden flies to escape and repeat the cycle at another inflorescence.12