Visit the Wikipedia (http://en.wikipedia.org/wiki/Portulaca_oleracea) which says, “Common Purslane, also known as Verdolaga, Pigweed, Little Hogweed, or Pursley, and Moss rose is an annual succulent in the family Portulacaceae”.
Interestingly, Purslane is edible. It is used much like spinach. Traditionally, it was used for medical purposes. We just enjoy the blooms!