Vegetation natural heritage can be valued in itself, but also as a habitat for many wildlife species. This study presents a methodological essay concerning the evaluation of plant heritage, applied in Central Alentejo, in the south of Portugal. This evaluation was based on the following criteria: horizontal and vertical structure of vegetation, tree cover density, rare plant species richness, phytocenotic maturity, importance as ecological corridor, historical record, scientific and educational potential and recreational potential. The vegetation heritage value (VHV) was calculated using a linear combination of the weighted criteria. In this way it was possible to identify the most interesting areas for conservation purposes. Of the 7500 km2 analyzed, 52% are natural and semi-natural areas, and of these, 18.8% have very high VHV, 70.7% have high VHV and only 10.5% average VHV. The highest VHV areas are actually included under the protected areas of Natura 2000 sites.