Screenshot of a microarray clustering tree validated and displayed with ETE. Expression profiles of terminal nodes (genes) are shown as a heatmap at the right side of the image. Silhouette indexes were calculated for each internal partition and are displayed in the tree. Size of green and red bubbles is proportional to the silhouette value. Red bubbles stand for silhouette values lower than 0 and green bubbles for silhouettes higher than 0. Two graphs representing the mean expression profile of the two most basal tree branches are also included in the image.