It is hard to tell when the plant parts are dried and preserved without a close look. For identifying the taxonomy of an unknown plants, it will be helpful when the info of their fruits, flowers and the architecture of the live plants are provided. Will It be possible to obtain a photo of its live plant?
Dear Emmanuel, could you give us an information on the color of the flowers? I agree it should be some Acanthaceae, but bracts seem to be rather small. So, it would not be Beloperone. Maybe this is some species of the large genus Justicia, similar to e.g. Justicia secunda? Where was the plant collected? In a botanical garden? Somewhere in the field in Nigeria? In what kind of vegetation?
Clearly Acanthaceae, but it would be good to have more field data, including locality where collected, habit, flower colour and a better close up of the flower to see calyx and open corolla