Caeau Tan y Bwlch ("the fields below the mountain pass") on the northern slopes of Bwlch Mawr represent some of the last unimproved fields left on the Lleyn Peninsula with clawdd (earth and stone) walls still in place. The meadows are grazed from September to April each year. Some of the drier meadows are cut for hay in late summer.
Wildflowers at the reserve - what to see and when
May: Cuckooflower, marsh violet
June: Adder's-tongue, greater butterfly-orchid, bogbean
July: Black knapweed, common bird's-foot-trefoil, heath spotted-orchid
August: Devil's-bit scabious
The upper fields at Caeau Tan y Bwlch support common knapweed, bird's-foot-trefoil, lady's-mantle, adder's-tongue fern, heath, common spotted-orchid and greater butterfly-orchid.
On the lower, wetter slopes a variety of ferns, sedges and other water-loving plants thrive, such as wood horsetail, marsh violet, bogbean, cuckooflower and Devil's-bit scabious.