The River Cegidog is a river in north-east Wales

Wales

Wales is a country that is part of the United Kingdom and the island of Great Britain, bordered by England to its east and the Atlantic Ocean and Irish Sea to its west. It has a population of three million, and a total area of 20,779 km²...

. It flows mainly through Flintshire

Flintshire

Flintshire is a county in north-east Wales. It borders Denbighshire, Wrexham and the English county of Cheshire. It is named after the historic county of Flintshire, which had notably different borders...

 but towards the end of its course it forms the border between Flintshire and Wrexham County Borough

Wrexham (county borough)

Wrexham is a county borough centred on the town of Wrexham in north-east Wales. The county borough has a population of 130,200 inhabitants. Just under half of the population live either within the town of Wrexham or its surrounding conurbation of urban villages. The remainder living to the south...

.

Its source lies in the hills of southernmost Flintshire to the east of Rhydtalog

Rhydtalog

Rhydtalog is a small, isolated village in Flintshire, Wales. It lies in hilly country on the border with Denbighshire in the community of Treuddyn....

 village. It flows in a roughly north-easterly direction before turning south east through the villages of Llanfynydd

Llanfynydd, Flintshire

Llanfynydd is a village and local government community in Flintshire, north Wales. Its name is derived from the Welsh words llan, "church" or "parish", and mynydd, "mountain"....

 and Ffrith

Ffrith

Ffrith is a small village in the community of Llanfynydd in Flintshire, north-east Wales.-Name:The name Ffrith reflects a spelling and pronunciation particular to Flintshire: it is derived from a North Welsh word meaning variously a "pasture", "enclosure" or "forest" and borrowed originally from...

 where the Nant-y-Ffrith

Nant-y-Ffrith

Nant-y-Ffrith refers to a stream and the wooded valley through which it flows on the border between Flintshire and Wrexham County Borough in Wales. The stream begins in moorland to the east of Llandegla. It passes Bwlchgwyn village before entering a rather steep-sided, rocky valley...

 stream flows into it. It then heads north-east again through a wooded valley before joining the River Alyn

River Alyn

The River Alyn is a tributary of the River Dee. The River Alyn rises at the southern end of the Clwydian hills and the Alyn Valley forms part of the Clwydian Range Area of Outstanding Natural Beauty...

 at Cefn-y-bedd

Cefn-y-bedd

Cefn-y-bedd is a village in Flintshire, north-east Wales.Cefn-y-bedd is on the A541 road to the south of its junction with the A550 road at Abermorddu. The village is served by Cefn-y-Bedd railway station on the Borderlands Line, linking Wrexham and Bidston on the Wirral Peninsula.- External links :*...

.

The name of the river indicates a place where hemlock

Conium

Conium is a genus of two species of highly poisonous perennial herbaceous flowering plants in the family Apiaceae, native to Europe and the Mediterranean region as Conium maculatum, and to southern Africa as Conium chaerophylloides....

grows.