Plantwatch: the plants that kill their insect pollinators

There are two plant species with the most brutal flowers in the world. The flowers of jack-in the pulpit, Arisaema angustatum, and its close relative Arisaema peninsulae are hidden inside a bowl-shaped wrapper with a tall hood. The male gnats may be tricked into finding a mate by imitating the sexy scent of female gnats.

Male flowers cover the gnats in pollen when the plants are small. The gnats can't climb out of the floral prison because it's too slippery, and they have to fly off and fall for another plant. gnats falling into the floral prison now become well and truly imprisoned because the escape hole closes as the plants grow larger. The gnats die because they smother the female flowers with pollen, but with no escape route and no food, the cruellest cross-pollination strategy of any known flower.