An ecological study based on the natural regeneration of the undergrowth was carried out in the S. Lisowski botanical garden of the Faculty of Science, Kisangani University. A floristic inventory was conducted taking into account the height and diameter of all individuals. From this inventory, 3901 individuals have been recorded and grouped into 6 species, 6 genera, and 5 families; for the species assessed according to the scale of abundance – dominance of BRAUN BLANQUET, 8 species grouped into 8 genre and 7 families were counted. The obtained result show the dominance of the Leptonychia tokana (1232 feet or 31.58%) species, followed by Costus lucanusianus (881 individuals or 22.58%) and finally Tricalysia bequaertii (741 feet or 18, 29%). Among the Spectra evaluated according to the scale of abundance-dominance of BRAUN BLANQUET, Trachyphrynium braunianum and Anthurium ferrierense are the most abundant. The most represented families in the undergrowth of the garden are the Rubiaceae, Marantaceae, Malvaceae and Costaceae.