Offsets or seed in spring or summer Agave polyacantha var polyacantha is a beautiful tropical looking agave that I photographed at the New York Botanical Garden. I have been unable to find any information about it. If it becomes available, it is sure to become popular.
Aged plants start producing pups, and then emit a large spike.
When the spike has finished blooming and producing seeds, the rosette that bloomed dies. This site contains information and pictures for more than 2000 species of plants. The CD of the site Enjoy the much larger pictures.