I should take a picture, but perhaps you know the answer without looking.
The grass on my allotment has lots of what look like small yellowish bulbs (though I doubt they are) when you dig it up. Whenever I see drawings or photos of couch grass it never has any of these small bulbs on it.
So what kind of grass is this? Does anyone else it? I know it might not matter what kind it is, but I'd like to know if the grass can regrow from these 'bulbs' or not, so I know how scrupulous to be about disposing of them.