Biogeographically, Andalusia forms part of the Western Mediterranean subregion of the Mediterranean Basin, which falls within the Boreal Kingdom. Five floristic provinces lie, in whole or in part, within Andalusia: along much of the Atlantic coast, the Lusitanian-Andalusian littoral or Andalusian Atlantic littoral; in the north, the southern portion of the Luso-Extremaduran floristic province; covering roughly half of the region, the Baetic floristic province; and in the extreme east, the Almerian portion of the Almerian-Murcian floristic province and (coinciding roughly with the upper Segura basin) a small portion of the Castilian-Maestrazgan-Manchegan floristic province. These names derive primarily from past or present political geography: “Luso” and “Lusitanian” from Lusitania, one of three Roman provinces in Iberia, most of the others from present-day Spanish provinces, and Maestrazgo being a historical region of northern Valencia.

In broad terms, the typical vegetation of Andalusia is Mediterranean woodland, characterized by leafy xerophilic perennials, adapted to the long, dry summers. The dominant species of the climax community is the holly oak (Quercus ilex). Also abundant are cork oak (Quercus suber), various pines, and Spanish fir (Abies pinsapo). Due to cultivation, olive (Olea europaea) and almond (Prunus dulcis) trees also abound. The dominant understory is composed of thorny and aromatic woody species, such as rosemary (Rosmarinus officinalis), thyme (Thymus), and Cistus. In the wettest areas with acidic soils, the most abundant species are the oak and cork oak, and the cultivated Eucalyptus. In the woodlands, leafy hardwoods of genus Populus (poplars, aspens, cottonwoods) and Ulmus (elms) are also abundant; poplars are cultivated in the plains of Granada.

The Andalusian woodlands have been much altered by human settlement, the use of nearly all of the best land for farming, and frequent wildfires. The degraded forests become shrubby and combustible garrigue. Extensive areas have been planted with non-climax trees such as pines. There is now a clear conservation policy for the remaining forests, which survive almost exclusively in the mountains.