In this paper, we propose a practical structured constellation for non-coherent communication with single transmit antenna over flat and block fading channel without instantaneous channel state information.The constellation symbols belong to the Grassmannian of lines and are defined up to a complex scaling.The constellation is generated by partitioning the Grassmannian of lines into a collection of bent grids and defining a mapping onto each of these bent grids such that the resulting symbols are approximately uniformly distributed on the Grassmannian. With a reasonable choice of parameters, this so-called cube-split constellation has higher packing efficiency, represented by the minimum distance, than other structured constellations in the literature. Furthermore, exploiting the constellation structure, we design low-complexity greedy symbol decoder and low-complexity log-likelihood ratio computation. Numerical results show that the performance of the cube-split constellation is close to that of a numerically optimized constellation, and better than other structured constellations. It also outperforms a coherent pilot-based scheme in terms of error probability and achievable data rate.