Obviously, this is not a commonly planted Lagerstroemia in our landscape. My very observant colleague informed me that he saw it planted along the roadside at Toa Payoh and I confirmed his observation when I drove past the area.
This tree does not have a very dense crown and when it flowers, most of its leaves are shed. But the relatively large purplish-white flowers do have its allure, as evident from these photos taken on 8 Mar 10.