| No | 20 |
| Common Name: | St John’s Wort |
| Scientific Name: | Hypericum perforatum |
| Irish Name: | Lus na Maighdine Muire |
| Family: | Hypericaceae. |
| Habitat: | This wildflower is found in grassy places, open woodland and road verges |
| Uses: | St John’s-wort is widely used in medicine as a treatment for depression and as an ointment for skin problems such as eczema. It is a prescription-only medicine. |