| Periwinkle, Greater | VINCA MAJOR |
| Periwinkle, Lesser | VINCA MINOR |
| Pineappleweed | CHAMOMILLA SUAVEOLENS |
| Poppy, Common | PAPAVER RHOEAS |
| Poppy, Opium | PAPAVER SOMNIFERUM |
| Primrose | PRIMULA VULGARIS |
| Purging Buckthorn | RHAMNUS CATHARTICUS |
| Purple Loosestrife | LYTHRUM SALICARIA |
| Ramsons | ALLIUM URSINUM |
| Raspberry | RUBUS IDAEUS |
| Rowan, Mountain Ash | SORBUS AUCUPARIA |