Puszcza Darżlubska is European Beech (Fagus sylvatica) forming thickets with pine and other coniferous trees. The area is covered mainly by coniferous forest in which the dominating tree is beech forming lowland groves. The beech is relatively young in the region. After the retreating glacier and the gradual warming of the climate around c.8,000 BC, the whole area was first covered by tundra. Along with the rise of temperature, the flora of the tundra gave way to new forest ecosystems in which most prominent were birches (Betula), pines (Pinus) and hazel (Corylus). The ecosystem of the primeval forest changed again with additional,
Fagus sylvatica depends on the location: in forest areas, "F. sylvatica" grows to over , with branches being high up on the trunk. In open locations, it will become much shorter (typically ) and more massive. The leaves are alternate, simple, and entire or with a slightly crenate margin, 5–10 cm long and 3–7 cm broad, with 6–7 veins on each side of the leaf (7–10 veins in "Fagus orientalis"). When crenate, there is one point at each vein tip, never any points between the veins. The buds are long and slender, long and thick, but thicker (to ) where the buds