What reason does this little piece of plastic grass serve? Decoration, duh.  After all, nothing increases the delicious presentation index like a little polyethylene terephthalate. 

But in this case, our petroleum product has an actual purpose and history.  The story behind plastic sushi grass (known on tatami mats as haran or baran) also has a story. Alice Gordenker, an American living in Tokyo and writer for The Japan Times, tells it nicely with the help of Ayao Okumura, a chef and food consultant.