I think Les might be referring to static grass, which does stand up,distinguishing it from grass mats or normal flock.
I've not used it, but it does look good around figures' feet.

Static grass is "true flock", you just get so mnay other products like- dyed sawdust, chips, fibres etc pretending to be flock, its become a general term now- like Hoover the brand is generally used to describe any kind of vacuum cleaner.