According to the scheme of origin and the evolution of organisms, the relicts are “old” taxons, which had a much wider geographic distribution in the past.

The flora of the Nature Park is distinguished by its large number of species that were particularly widespread during the Tertiary (Tertiary relicts) – 63 species. Seven of the species that can be seen on the European continent are found only in Strandja.

Amidst this variety, the Rhododendron ponticum, the Daphne pontica and more rarely the Vaccinium arctostaphylos and the Quercus hartwissiana, are often the key players and formers of the vegetative communities, while the rest are species of greatest conservation importance – the Ilex colchica, the Strandja Veronica turrilliana and the Epimedium pubigerum.