The scientific name of Mirabilis refers to a genus of plants, not a specific species. It is therefore correct to say the scientific name is Mirabilis.
Understanding Mirabilis
Mirabilis is a genus belonging to the family Nyctaginaceae, commonly known as four-o'clocks or umbrellaworts. A well-known species within this genus is Mirabilis jalapa.
Mirabilis jalapa: A Specific Example
According to the reference provided:
Mirabilis is a genus of plants in the family Nyctaginaceae known as the four-o'clocks or umbrellaworts. The best known species may be Mirabilis jalapa, the plant most commonly called four o'clock.
Therefore, if you're interested in a specific plant within the Mirabilis genus, a common example is Mirabilis jalapa.