Only a mile or two separates them but the Pegsdon Hills and Oughtonhead Common have a very different flora. The hills are grasslands on free-draining chalk. The common is marshland on a pocket of boulder clay. Here the waters from the hills feed the springs which bubble up at the head of the River Oughton.

 Hemp Agrimony (Eupatorium cannabinum) is much in evidence along with other species that need a damp habitat: Meadowsweet, Purple Loosestrife, Marsh Orchid et al. To quote Brian Sawford: "Marshes fed with highly calcerous waters can support a great variety of wildflowers."