Very little literature on root developmental patterns of forage or turf grass roots, is available.  Existing technology also has significant drawbacks when measuring roots finer than 0.5 mm diameter.  We have developed a system of scanners built into meso-rhizotrons (intermediate sized rhizotrons - 200 x 254 x 10 mm).  With these Aeroponic Scanning Meso-rhizotrons (ASM) we are documenting the developmental patterns of root growth of Lolium perenne L. (Perennial Ryegrass) and Schedonorus phoenix (Scop.) Holub (Tall Fescue).  Several “movies” will be shown to demonstrate the existence of extensive genetic variability within “cultivars” of these two species.  The impact of computer based image analysis on our ability to accurately document this variability will be discussed.  Finally, the potential of the ASMs for use in physiological studies, including pulse chase type studies will be discussed.