Containers of takeout sushi in America don't tend to vary too drastically from one vendor to the next. They usually come with a dab of mossy-green wasabi (actually mustard and horseradish). They may feature California rolls (actually Canadian). And they almost always come with a strip of fake, plastic grass separating the components.
That last part may seem like a distinctly American invention, but it actually comes from a centuries-old practice that's vital to Japanese cuisine, according to The New York Times.
Traditionally, haran (from the Japanese ha for leaf and ran for orchid or lily), also known as baran, is made from fresh leaves, not brightly colored plastic. By nestling a watertight leaf between two foods like fish and rice, Japanese chefs are able to preserve the natural flavors of the ingredients and stop scents from co-mingling.
Today, when Japanese chefs pack their bento boxes with fresh leaves, they often use bamboo leaves. Not only do these leaves keep odors from spreading, but they're also antimicrobial, which means they can slow bacteria growth and extend a meal's expiration date. Baran is so common in Japanese cuisine that there's even an entire art form called sasagiri that involves cutting the leaves into intricate patterns.
In recent decades, though, plastic barriers made to look like grass have started to gain popularity in both the United States and Japan. Fake grass may not look as pretty as the fresh leaves, but it is much cheaper—it cost $6 to supply 1000 to-go boxes, or 0.6 cents per swatch.
[h/t The New York Times]