Oh that is very difficult to do even for experienced with grasses...as we talking about improved cultivars from regular rye..note cultivars..all the identification points will be so similar/same that without actually letting the grass grow its mature state you'll be struckling...
"Dwarf" in this case will just mean (depeding cultivar used) finer and/or low-growing...but within fine turf grasses even finer cultivars will look course.. ::)
