It is also called Mirabilis, or Marvel of Peru, or "Purple Jasmine". The plant is called Four O’clock because it tends to flower in the late afternoon. It is not actually the time of day that causes the flowers to open, but the drop in temperature. And so the flowers are still open in the early morning before I go to work.
The flowers are extremely fragrant - I suspect that might be the reason why it is called "Purple Jasmine".. And they attract nocturnal pollinators like moths!
The flowers are used in food colouring. And the leaves can apparently be used to reduce inflammation.
The seeds however, are extremely poisonous, leading one website to call it the "fatally fragrant flower"
Such an interesting plant!
Photo from here