I think they're plastic, but they're probably imitating horsetail fern. I love this look, and I love the look even more when they've got their tops thick and evened up. A nice straight haircut. I tried to grow these myself with disaster... I'd suggest you read up on how to care for them first before attempting... or perhaps just buy the plastic ones. I googleimaged this pic... shows it sells for about twenty bucks for 9" "plant"

sorry, link to choose file didn't light up, so I couldn't attach the picture...