It's a grass...but certainly not a bamboo.

Interesting. Will loop back when this grows up.

And just FYI for the future: when you buy bamboo seeds online from sellers outside the U.S., and they are imported, it's a violation of federal regulations. If your purchase gets inspected coming into the U.S. it will be confiscated, and you may be contacted by the USDA or U.S. Customs.

On the other hand, if you're not located in the U.S., don't worry about it.

Seedling asked about here looks pretty similar to Phalaris arundinacea. As I remember it the J. numbers refer to individual seedlings grown from seeds collected comparatively recently there, it wouldn't ordinarily be expected that these same still young plants would now be producing their own seeds. Unless somebody is using "4" to refer to a subsequent collection of additional seeds in J. - and not a western horticultural selection. Including one that became known as Red Panda in Britain.

Thank you! Does look similar. I might as well watch this grow given the time I spent nuturing the seed even though wasn't what I expected