Fig. 4. Biomass from clippings (dry weight) of tall fescue (TF), Kentucky bluegrass (KBG), and two hybrid bluegrasses (HBG1 and HBG2) during 2003. Means followed with the same letter within each respective day of year (vertical) are not significantly different (P < 0.05).

Image from Applied Turfgrass Science article:
Performance in the Transition Zone of Two Hybrid Bluegrasses Compared with Kentucky Bluegrass and Tall Fescue