A system and method for grouping cluster spines into a two-dimensional visual display space is provided. Clusters of concepts, each extracted from documents, are obtained. Spines are formed by placing the clusters sharing at least one of the concepts along a spine. The spines are ordered based on a length of each spine. One or more of the spines are selected as unique spines and placed into a visual display space. A similarity is determined between one of the spines not placed and each of the placed unique spines. The placed unique spine most similar is identified. An anchor cluster on the most similar unique spine that satisfies a threshold similarity with the unplaced spine is selected. A cluster on the unplaced spine that is most similar to the selected anchor cluster is identified and grafted to the selected anchor cluster as a group of cluster spines.