Llyn Bedydd is a small lake in Wrexham County Borough, in northeastern Wales, near the border with England.
[1] Llyn Bedydd is 1 hectare (2.5 acres) in area[2] and is surrounded by carr woodland of willow and alder which merges into drier deciduous woodland dominated by downy birch and sycamore higher up the slope.
[3] The wet carr around the Llyn Bedydd is notable for purple small reed and alder buckthorn which are very rare in Clwyd; tufted sedge and bay willow which are uncommon in Clwyd; and the nationally scarce cowbane.
The fen creates a tussocky species rich floating mat at the southern end of the lake while on the land in the southeastern corner of the SSSI there is a small area of fen pasture which grades into a bog.
Llyn Beddyd is relatively shallow but it has steeply shelving banks which are shaded by the woodlands and these restrict the development of stands of emergent and marginal vegetation.