By Sheryll
United Kingdom 
I purchased a "black" grass years ago, which was kept in an earthenware container. It was transferred to the ground last year, but now there is a lot of "new" grass appearing next to it, which is GREEN, is this related to our old plant, or something new. I have no idea what it is called!
12 Aug, 2012
Answers
Most likely its just new growth which, as Owdboggy says, starts out green.
12 Aug, 2012
Thanks very much, I will keep my eye on it, and hopefully I will have lots of lovely BLACK grass in the future.
Sheryll
12 Aug, 2012
yes agree with the above, once they get going they quickly form a good mat of grass, very easy to propagate just divide and plant elsewhere, you will see purple berries in time the seeds are easy to propagate too, they look great in terracotta plant pots on their own or in a large pot with yellow tyme.
12 Aug, 2012
?Ophiopogon planiscapus nigrescens is commonly called Black Grass. If it seeds itself then 2/3 of the new ones have reverted to the original green colour. Also new growth does start off green and then turns darker as it matures. Easy enough to tell, trace the new growth back to the original plant.
12 Aug, 2012