When an ornamental goes bad!

Pretty spikelets of Chasmanthium latifolium

Most ornamental grasses behave themselves. They do what they're supposed to do. They sit where they've been placed and look pretty for all the guests.

But there are a few ornamentals that don't stick to the rules. They waylay unsuspecting gardeners with their beauty, but once they've gotten safely tucked into the soil, they slowly show their true colors.

At first there are just a few new culms coming out, their appearance causing the gardener to exclaim in delight. But soon there are more than just a few of these sprouts, and before long the new grass is starting to take over the land, crowding out other plants.

Rhizome and roots of Chasmanthium latifolium

Chasmanthium latifolium is known by many common names, including woodoats, inland sea oats, northern sea oats, and river oats. It has attractive light green foliage and unique hanging inflorescence that vibrate in the slightest breeze. 

It is also a rhizomatous species that is a prolific seed producer, and the unwary owner soon finds his garden starting to be overrun by this ornamental grass. In the case of the image below, a few transplants spread throughout the path and sides of the path, growing between the stepping stones.

Chasmanthium latifolium taking over garden

It has even started crowding out any nearby plants, the beautiful flowerheads rising above the surrounding vegetation like some conquering army proclaiming victory over its competitors. In the case of the unfortunate iris below (in the foreground, with larger broader  leaves), C. latifolium has enveloped it from the back with masses of smaller leaves.

Chasmanthium latifolium crowding out Iris from behind

In the end it is up to the owner to make sure that the pretty ornamental that he or she plants will not suddenly become too aggressive and uncontrolled in the garden. Grasses that have rhizomes and are prolific seed producers need to be used with care. Do your homework, and always remember that these grasses are living things, and that they do not exist for you but for their own ultimately selfish reasons.