Dendrogram source extraction from the N_H2 and CO maps. Left: GMC detections outlined by the lowest level branches in the dust-derived N_H2 map (green contours) and 326 leaf structures (red contours). NGC 604 is marked with a thick pink contour. Right: GMC detections identifying 199 leaf structures in the line-integrated CO(2 − 1) map (blue contours) and similar to the dust map, the branches (green contours). The small circle in the lower left corner of both figures shows the beam size of 18.2″.