The location just to the east of Wallace’s line gives the islands a transitional biota between the Oriental and Australasian regions. The predominant vegetation, covering some 70% of the Park, is dry open grass-woodland savannah, mainly of anthropogenic origin, Most of its species are xerophytic with water-retaining adaptions and many are fire-adapted. There are also patches of tropical rainforest, deciduous monsoon forest and mangrove. The dominant savannah tree is lontar palm Borassus flabellifer, which occurs individually or in scattered stands. Grasses include Eulalia leschenaultiana, Setaria adhaerens, Chloris barbata, Heteropogon contortus and, in the higher areas,Themeda spp. including T. frondosa and T. triandra. Tropical deciduous monsoon forest occurs along the bases of hills and on valley bottoms, characterised by trees such as Sterculia foedita, Oroxylum indicum, Tamarindus indica, Zizyphus horsfeldi, Schleichera oleosa, Cassia javanica, Murraya paniculata, Diospyros javanica, Harrisonia brownii and Piliostigma malabaricum. The forest lacks the predominance of Australian-derived trees and flora found further to the east on Timor (Sumardja, 1981).
A quasi cloud-forest occurs above 500m on pinnacles and ridges. Although covering only small areas on Komodo Island, it harbours a relict flora of many endemic species (Auffenburg, 1980). It is characterised by moss-covered rocks, rattan, bamboo groves and many trees generally absent at lower elevations. These include Terminalia zollingeri, Podocarpus neriifolius, Uvaria rufa, Ficus drupacea, Callophyllum spectabile, Mischocarpus sundaicus, Colona kostermansiana and Glycosmis pentaphylla. The three main coastal marine vegetation types are mangroves, sea grasses and reef-building coralline algae. The mangrove forest occurs in sheltered bays on Komodo, Padar and Rinca. There are 19 species dominated by Rhizophora stylosa, R. mangle and Bruguiera gymnorrhiza, with Avicennia marina in large stands on the landward side (Sumardja, 1981; PHKA, 2004). Other coastal vegetation includes pioneering beach plants like Ipomoea pes caprae. Due to the dry climate, plant species diversity is relatively low, with only about 102 recorded species (PHKA, n.d.). Extensive sea grass beds of Thalassia hemprichii and Zostera capensis occur off the north end of Rinca Island (Kvalvagnaes & Halim, 1979)