Since pre-European settlement, major alterations to the native landscape have been made, due largely to urban and agricultural developments. In south Florida, these activities have caused extensive degradation to native plant communities leaving remnant native lands. Therefore, the floristic quality of these native lands is changing, and a tool to assess their quality is needed. Assignment of coefficient of conservatism (C) values (ranging from 0 to 10) to each native plant within south Florida allows for the use of the floristic quality index (FQI), a tool to assess the quality of natural or remnant native plant communities. The coefficient of conservatism concept is based on two factors: 1) plants have various degrees of fidelity to specific habitats and their quality, and 2) plants have varying tolerances to disturbances and respond in various degrees. The establishment of C values and the use of the FQI eliminate subjectivity and provide a standardized method to evaluate the floristic condition of a site, which allows for comparisons between different sites and monitoring of sites over time. Non-native plants are not assigned conservatism coefficients values because they did not evolve in the native landscape. In south Florida (Florida Keys excluded), there are approximately 2226 plants, of which 64% (1434) are considered native and 36% (792) are considered non-native. Of the 1434 plants examined, only 94 native plants remained unranked, because the team did not have enough experience with the plant to confidently assign a C value. Approximately 33% of plants ranked fell into the ruderal categories (0–4), whereas 67% fell into obligate to natural areas categories (5–10). Once a thorough inventory of a site has been completed, a mean C value and FQI can be calculated.