One of my favorite Chicago haunts is the Garfield Park Conservatory on Central Park just north of Lake Street. It has an Aroid House, which is a large room containing all sorts of aroids, spiky plants belonging to the Araceae family.
Plant size and form vary considerably.
Bunny Ears Cactus. Notice the tiny white clusters of glochids.
Yellow Tower. 
Aeonium.
Golden Barrel Cactus.
And Queen Victoria Agave.
Admire with ease, but handle with caution.
must love biscuits 