Phylogenetic tree constructed with 400 target stellar particles randomly selected from the inner ring. Colour indicates the age of the stellar particles (left), their iron abundance ([Fe/H]; centre), and their oxygen and nitrogen abundance ([O/Fe] and [N/Fe]; right). Branch lengths are shown to scale only in the leftmost tree; in the other panels the trees are laterally shifted for easier visual comparison. The x-axis is displayed on a power-law scale to enhance visual clarity. The boxed region highlights the main clade discussed in the text. The root is located at the top left of each tree and is highlighted by a red contour.