The mountains in the park are covered in forests of Japanese beech and other broadleaf deciduous trees up to an altitude of around 1,500 m; at higher altitudes, subalpine coniferous forests of Japanese hemlock and Maries' fir can generally be seen.
In addition, many mountains in the park have unique plant life due to differences in topography, the periods in which landforms were created through volcanic activity, and the heavy snowfall during winter.
Low trees and shrubs such as mountain ash, heathberry, and bog whortleberry can be seen on still-active volcanoes such as Mt. Kusatsu-Shirane, where forests do not grow.
On Mt. Kusatsu-Shirane and the Shiga Highland (Shiga Kogen), Siberian dwarf pine grows even at altitudes of 2,000 m or less, and alpine floras can be seen on the scree slopes characteristic of volcanoes.
Subalpine coniferous forest (Mt. Shigayama)
Many of the high moors and lakes on Mt. Naeba and the Shiga Highland (Shiga Kogen) developed in the uneven surfaces of lava rock and other volcanic ejecta, and the park has a diverse range of flora, including Scirpus hotarui communities.
In this park, it is possible to see various plants that are peculiar to mountains and highlands. In particular, the alpine floras growing in subalpine belt, flowers blooming in wetland areas, and Japanese azalea growing on the Yunomaru Highland in particular are all very well-known, and many people visit the park to see them.
High Moor (Shijuhachiike Marshland)