1. A system for grouping cluster spines into a two-dimensional visual display space, comprising: a spine generator to obtain clusters of concepts each extracted from one or more documents and to form spines by placing the clusters sharing at least one of the concepts along a vector; a spine ordering module to order the spines based on a length of each spine; a spine placement module to select one or more of the spines, each unique from the other spines, as unique spines and to place the unique spines into a visual display space; a similarity module to determine a similarity between at least one of the spines not placed and each of the placed unique spines and to identify the placed unique spine most similar; an anchor selection module to select at least one anchor cluster on the most similar unique spine that satisfies a threshold similarity with the unplaced spine; a grafting module to identify one of the clusters on the unplaced spine that is most similar to the selected anchor cluster and to graft the most similar cluster to the selected anchor cluster such that the unplaced spine is positioned along a vector extending from a center of the selected anchor cluster to form a group of cluster spines; and a display to display the group of cluster spines in the visual display space.