Indigograss

This large, yellow-green grass grows up to 5 feet (1.5 meters) tall. The broad, flat stalks grow in extensive patches that are flexible and they overwhelm an area rapidly.

When mature, the end of the stem eventually transforms into a small, indigo tuft.

During the mid-autumn, it produces lots of pollen; it can cause severe allergic reactions, and after flowering, it is left with a handful of giant grains.