Rainforest of the Congo Basin share many characteristics with the Amazon rainforest and other tropical forests worldwide: high diversity, dense vegetation, and multiple layers of forest structure. The forest canopy is usually about 30 meters tall, with emergent trees such as the great maobi reaching up to 50-60 meters. The most humid, western portions of the Congo basin forests remain evergreen throughout the year, while interior forests are semi-deciduous, and many species drop leaves for short periods of time. Peripheral forests of the Congo basin with less precipitation become even more deciduous, although trees usually grow foliage on some branches before other branches lose their leaves.
Forests of the Congo Basin are characterized by fewer species of trees than the Amazon rainforest. In the interior of the Congo, forests are dominated by heavy seeded, shade tolerant trees of the Caesalpinoid subfamily of the legume family, such as Julbernardia and Cynometra species. Other areas of mature forest include the monodominant stands of Gilbertiodendron dewevrei, also a member of the legume family. Heavy seeded and shade tolerant trees such as these often have greater success seeding and surviving in the shade of the mature forest. In open, more disturbed habitats of secondary forest however, sun loving, light seeded trees dominate, such as Entandrophragma and Khaya species, both members of the African mahogany group, as well as species of Albizia. In younger secondary forests, early pioneers such as Musanga cecropiodes are more common.
In mature forest, understory plants are dominanted by shade tolerant families such as Maranthaceae and Zingiberaceae. Although not as well documented as in the Amazon, studies have found lianas to be a significant component of forest structure and diversity, comprising approximately 25% of the total diversity of woody species. In one study of the Ituri forest in northeastern DRC, liana diversity is dominated by Manniophyton fulvum (Euphorbiaceae). Epiphytes such as orchids and mosses are also much less common in the Congo forest as compared to the Amazon rainforest, likely due to the dry climatic history of the Congo Basin. Diverse epiphyte families of the Neotropics such as the cactus and the bromeliads are largely absent from central Africa, but at least 2,400 species of orchids are still present throughout the humid forests of Africa. Other native herbaceous plants include numerous species of Begonia and Impatiens.
