The flora of the Natural Park of Southwest Alentejo and Costa Vicentina is split into three types of geomorphological environments:
Western barrocal in Vincentian plateau south, with vegetation typical of calcareous soils, in a dry and warm climate zone;
coastal plateau, with more diverse vegetation on the dunes, heathland and wetlands.
coastal mountains and bounds, more fresh and moist, with dense tree and shrub vegetation bordering the streams.
Throughout the park there is a mix of Mediterranean vegetation, North Atlantic and African, predominantly to first. There are about 750 species, of which more than 100 are endemic, rare or localized; 12 there are nowhere else in the world. In the park area are considered vulnerable species in Portugal, as well as several protected species in Europe.
Among the endemic species there are, for example, plants such as: Biscutella vicentina, Scilla, Vincentian Centaurea, Vincentian Diplotaxis, Vincentian Hyacinthoides, Cistus palhinhae, Plantago almogravensis. Other species are considered rare as Samouco (Myrica faya), the rowan (Sorbus domestica) or Silene rotlunaleri. However farming has led to the extinction of plants such as arcuata Armeria.
The tree species in the park area are divided into components classified as natural and artificial. The former are dominated by oaks, such as cork oak (Quercus suber) and cerquinho oak (Quercus faginea), particularly in bounds. The strawberry tree (Arbutus unedo L.) is also characteristic of this area.
Tree species classified as introduced are mainly the-pines (Pinus pinaster), eucalyptus (Eucalyptus globulus) and acacia (Acacia spp.).