Figure 6. Comparison of abundance of selected pyrrolizidine alkaloids (PAs) in roots and shoots of Senecio vulgare plants grown under uniform conditions in the greenhouse.

Plants were grew from seeds collected from 6 native and 6 invasive populations. Clustering algorithm and Euclidean distance metric were used on relative abundance values. See details of key to populations (at leaf of heatmap) and to PAs (on the top of heatmap) in Tables 1–3. The relative abundance of the 13 selected PAs was at least 1%, averaged among all samples.