Oxalis triangularis (commonly called false shamrock), subspecies O. triangularis subsp. papilionacea. As a pot plant is known as love plant or purple shamrock.
Taken by <a href="//commons.wikimedia.org/wiki/User:Fanghong" title="User:Fanghong">Fanghong</a>
CC BY 2.5
<span class="int-own-work" lang="en">Own work</span>