Lush dipterocarp forest vegetation and lianas cover the lower regions
giving way to thick damp mossy forests as the altitude gets higher and
temperatures get cooler.
The variety of plant life found within the park include Agathis, Mountain
Ru, Tree ferns, different species of orchids and begonia. A particularly
interesting specie is the Mengaris tree whose smooth grey trunk makes it
particularly difficult to climb. Wild bees protect their precious store
of honey from the voracious honey bears, by making their honeycombs high
up these trees.
The 'Orkid Telinga Gajah (Phalaenopsis gigantea)
is a wild orchid endemic only in Borneo and in Sabah this orchid
species is only found in Tawau Hills Park and Tenom.
This orchid is unique as some may have up to six leaves as compared
to three and four in other wild orchids. Its flowers would bloom
only twice in three years and the flowers can last up to six months,
apart from fetching the price of RM10,000 per plant.
Botanical Garden has some 200 species of
orchids and about 6,000 of orchid plants.
Apart from orchids, the Botanical Garden also showcases some 60
species of ferns including the giant ferns, 43 species of 'halia
hutan' (globa panicoides), wild yam (Colocasia esculenta) and herbs
such as 'Tongkat Ali', 'Kacip Fatimah' and incense wood.