Location: Scottsdale, AZ
While this agave plant appears to be thriving, it's actually dying. That's because the Agave Americana shoots up a stalk with bright, yellow flowers only once and that occurs only as it nears the end of its life.
This stalk is approx. 15 feet tall, although they can reach up to 30 feet depending on the size of the plant sprouting it. These stalks grow amazingly quickly -- typically, several inches a day, although they can sometimes grow up to one foot per day! -- and they're quite substantial, too. If one should happen to fall on your head as you walk past, it will definitely leave a mark.