Why would gardeners want to grow aconitums in their gardens?

Aconitums, commonly know as Monkshoods, are poisonous plants with tall, spiked flower heads.
The blue and purple flowers of the plant bloom in late summer. The aconitum grows well throughout the mid-section of the United States. Aconitum is best used as a border along the back of
a garden

A.) They draw butterflies.
B.) They keep insects away.
C.) They will serve as a beautiful backdrop.