Spotting

This is what Wikipedia says, "A curious aspect of M. jalapa is that flowers with different colours grow simultaneously on the same plant.


Different color variation in the flower and different color flowers in same plant.

Variegated flower on a four o'clock plant.

Naturally occurring color variation on four o'clock flowers.
Additionally, an individual flower can be splashed with different colours. Flower patterns are referred to as sectors (whole sections of flower), flakes (stripes of varying length), and spots. A single flower can be plain yellow, pink or white, or have a combination of sectors, flakes and spots."
We have this plant in India too...usually yellow and magenta.