Besides the high diversity of animals and birds, the flora of the Batang Toru Ecosystem is also fantastic, with a mosaic of differing forest types.

FLORA

Species from the families Sapotaceae, Myrtaceae, Lauraceae, Anacardiaceae and Fagaceae dominate the tree flora. However, several species of an ancient family of trees, the Podocarpaceae, such as the sampinur bunga and sampinur tali, and Nageia neriifolium, are also common, and the fruits of these 3 species are favourites of the unique Batang Toru orangutans.

Since 2007, YEL staff have been monitoring the monthly phenology (flowering, fruiting, leaf production) of more than 1500 trees to determine the productivity of the Batang Toru Ecosystem.

Because most of the Batang Toru Ecosystem  is more than 800 m above sea level, relatively few species of the economically important Dipterocarpaceae are encountered, but some of those that do occur are in the IUCN red-list.

Several threatened flora occurring in the Batang Toru forests

No. Species Status
1. Dipterocarpus crinitus EN (IUCN)
2. Shorea platyclados EN (IUCN)
3. Shorea acuminata CR (IUCN)
4. Nepenthes spp PP nomor 7/1999
5. Gonystylus macrophyllus Appendix II (CITES)

Many orchid species have been found on the steep mountainous slopes, and several other interesting groups have been encountered such as parasitic plants from the Balanophoraceae family. The very rare giant rafflesia flower, Rafflesia cf micrpylora-gadutensis, has been encountered by only in the low area of the foothills facing the Indian Ocean, and this area has already been cleared by a gold mine. Twelve species of pitcher plants (Nepenthes spp.) have been found in the Batang Toru Ecosystem so far.