The ancient principle of trapping insects as a means of ensuring pollination was readopted by some advanced families (e.g., orchids and milkweeds), and further elaboration perfected the flower traps of primitive families. The cuckoopint (Arum maculatum), for example, attracts minute flies, which normally breed in cow dung, by means of a fetid smell. This smell is generated in early evening, along with considerable heat, which helps to volatilize the odor ingredients. The flies visiting the plant, many of which carry Arum pollen, enter the floral trap through a zone of bristles and then fall into a smooth-walled floral chamber from ...(100 of 4677 words)