Oxalis regnellii var. triangularis
The Purple Oxalis (oks-AL-iss) is sometimes called the Love plant, Purple shamrock, or False shamrock. It is a member of the Wood sorrel family.
The leaves of the plant close at night. From the Wikipedia website…
“The leaves of O. triangularis move in response to light levels, opening in high ambient light (in the day) and closing at low light levels (at night). This movement is not due to growth and is instead powered by changes in turgor pressure in cells at the base of the leaf. It is an example of photonasty.”
The plant can survive severe drought and may even appear dead. However, when the it is watered again, it will rebound and flourish. Or, if you water it regularly and dead head the old blooms, it can continue to bloom for an extended period.