The end of the 18^th century is regarded the beginning of the botanical investigations in the present territory of the Neris Regional Park, when Mr J. E. Žiliberas (1741-1814) and Mr S. B. Jundzilas (1761-1847), the first botanists, having investigated the Lithuanian flora, travelled from Vilnius along the riversides of the Neris. Alone and together with the students of Vilnius University, they visited many vicinities of Vilnius, accumulated the first materials about the flora of the country. J. E. Žiliberas published the summarised data in Parts 4 and 5 of the five-volume work “Flora Lituanica Inchoata,” and S. B. Jundzilas published it in a book called “The Description of the Naturally Growing Flora in the Grand Duchy of Lithuania According to Linnaeus’s System.” These are the first works about the Lithuanian flora. A part of the 778 plant species described by J. E. Žiliberas and of the 1070 ones described by S. B. Jundzilas was undoubtedly found during the excursions down the Neris.  

    Today forests occupy a great part of the territory of the Neris Regional Park. The old cartographical material shows that at the end of the 19^th century and at the beginning of the 20^th century, there were far fewer forests here; therefore many of them now grow in the former farmland and meadows. Pine forests prevail, occupying 80 per cent of the total forest area of the park. Growing in a bit different plant habitats, they are not the same. Cowberry pine forests prevail in the driest parts of the continental terraces, on the sands and gravels that are the most barren in nutrient materials. Mixed cowberry-bilberry pine forests with spruces are found in the lower places of the terraces. Oaky pine forests, which most often lie on the steep slopes of the Neris and on the edges of the upper terraces, grow in the most fertile plant habitats, on the carbonaceous sands and gravels.  

    In the park there are a few spruce forests, and they do not compose major massifs. Leafy forests grow in small ranges in a great part of the park. In the valleys of small streams and on the lakesides quite often lie Alnus incana forests with the infusion of Prunus and Alnus glutinosa, and in springy underterraces of  the Neris valley, there are Alnus glutinosa forests hardly touched by economic activities. Their forest stand, besides Alnus glutinosa, is formed with Prunus and Fraxinus.

    The biggest massif of the broad-leaved forests in the territory of the park is Dūkštos oak-wood, which is the greatest and oldest oak-wood in Lithuania.

    731 plant species have been found in the Neris Regional Park, 44 out of them have been entered in the Red Data Book of Lithuania. Such a great variety is determined by the peculiarities of the soils and relief. For the protection of rare plant species, the botanical strict nature reserves of Bražuolė and Vepriai have been established. In the valley of the Bražuolė River, even 22 protected and several tens of quite rare plant species – the most in the entire park – have been found. The small lakes of Vepriai are overgrown with a continuous lane of relict sawgrass. The wetland between the small lakes, waterlogged spots and banks of the lake surroundings are the habitats of rare and protected plant species.