The vegetation
within the reserve can be broadly categorizes in to three main types based on topography.viz.the lower slopes and valleys (150-600metres), middle slopes (600-1000metres) and the upper slopes and ridges (above1000 metres).
The lower slopes and valleys comprise the peripheral parts of the Reserve. These areas would have contained Dipterocarpus zeylanicus(Hora) and D. hispidus (Bu Hora) as the dominant canopy trees reaching 45 metres and forming a clear emergent layer. However,today these areas are covered with secondary scrub and 'Kekilla' fernlands of Dichranopteris linearis. The only patches which have escaped destruction are a few along streams banks and valleys.
The forests which thrive on the middle slopes cover the greatest expanse. These are characterised by Mesua nagassarium(Batu Na), M. ferrea(Diya Na) and several Dipterocarp species belonging to the genus Shorea(Dun). They are popularly referred to as the Mesua-Doona(Na-Dun) community.These forests reach a height of 30 to 45 metres and have an unbroken canopy devoid of emergents.
Towards the upper slopes and ridges, the tree size decreases and on exposed summits such as Moulawella and Hinipitigala the trees assume stunted proportions which are typical of montane vegetation.
