| Author | Title | Journal/publisher | Literature ref. no. |
| Robyns, W. (1948) | I. Gymnospermes et Choripetales | Flore des Spermatophytes de Parc National Albert Institut des Parc Nationaux du Congo Belge | 1636 |
Note that the process of capturing references from species to the literature and the reverse may be incomplete.
| Species found: 3 |
| Piper guineense |
| Piper umbellatum |
| Podocarpus milanjianus |