Thirteen plant assemblages were delineated based on species composition from 425 stands representing grassland, shrubland and woodland vegetation types. The use of classification, ordination, and indicator species analysis produced ecologically realistic plant assemblages. Most of the assemblages were limited to exposed, southerly aspect sites with shallow, rocky, fast draining, loam soils. Some of the assemblages were fairly restricted by environmental conditions, while others were found in a number of ecological sites defined by topographic and edaphic characteristics. Some assemblages were discrete in regards to species composition, while others shared common species. Structural characteristics varied by assemblage, however, a high proportion of trees belonging to a young age cohort was common to most assemblages. The highest proportion of naturalized taxa is in the form of exotic annual grasses. This functional group is found in mostly low elevation, low canopy situations. The relatively high proportion of exotic annual grasses in the assemblage with the highest amount of recent disturbance suggests that wildfire and/or fuels reduction treatments may increase the proportion of naturalized taxa on a site. The fescue grassland and black oak woodland plant assemblages have the highest average stand richness and appear to be rare locally and perhaps regionally. These assemblages have a low relative abundance of sites and high species richness of mostly native plants, which warrants management to ensure their persistence on the landscape.