WAS ADDA ap IORWERTH?
By Darrell Wolcott
Peter Bartrum's chart for Iorwerth Drwyndwn ap Owain Gwynedd  includes a brother of Llewelyn (who was to become Llewelyn
the Great, King of Gwynedd) named Adda, He cites two sources to support his family placement for this Adda, both of
which involve a Marged ferch Gruffudd ap Gronwy who married y Pothan Flaidd, descended from Rhiryd Flaidd.
Peniarth Ms 287, 254 (which Bartrum accepts as "correct") cites that marriage as shown on the left below, while the
Dwnn ii, 290 version (which Bartrum marked as "corrupt") is shown on the right:
Iorwerth Drwyndwn Adda
Rhiryd Flaidd Ifor
l l l
Marged=====Y Pothan Flaidd Marged==Y Pothan Flaidd
We believe both citations contain errors in the ancestries of both the husband and wife and would correct the citations as
Rhiryd Flaidd  1155
Rhiryd Fychan 1250
1290 Marged==============y Pothan Flaidd 
*This cannot be Iorwerth Drwyndwn ap Owain Gwynedd, a man who was
born a generation earlier than 1155
When we extend the chart with some of the families who descended from Y Pothan Flaidd, it will confirm our chart and its dating:
(a) This Cadwaladr was "ap Meurig (1200) ap Sir Robert (1165) ap Madog Marchog
Dda (1135) ap Einion (1100) ap Sir Gwdrys/Goodrich (1070) ap William Lord D'elboeuf (1040), the latter being a son of the
sister of William of Normandy, King William I of England.
(b) Dwnn ii 290 & 334 all cite the marriage of
Dafydd ap y Pothan Flaidd to Sioned ferch Dafydd Fychan ap Dafydd ap Cadwaladr.
(c) This Philip Dorddu
is "ap Hywel (1290) ap Madog (1255) ap Hywel (1220) ap Gruffudd (1185) ap Gronwy (1150) ap Hoedliw Goch (1120) ap Rhys (1085)
ap Hoedliw (1055) ap Cadwgan (1020) ap Elystan Glodrydd."
(d) This Dafydd is "ap Ieuan Penaran (1305) ap Gruffudd (1270) ap Meilyr Penaran (1240) ap Cynwrig
(1205) ap Genillin (1170) ap Cynwrig (1135) ap Genillin (1100) ap Meirion Goch" (1070) descended from Collwyn ap Tangno.
(e) Dwnn i, 322 and Peniarth 135, 179
cite the marriage of Philip Middleton ap Rhiryd ap Dafydd ap y Pothan Flaidd to Angharad ferch Gruffudd Dwnn ap Philip Dorddu.
Pen 128, 661b cites the marriage of Dafydd Llwyd ap Gruffudd ap Dafydd to Gwen ferch Ieuan ap Dafydd.
The Marged in our first chart DID descend from an Adda ap Iorwerth, but this was NOT Iorwerth Drwyndwn ap Owain Gwynedd, a
man born c. 1128. We believe her ancestor was Adda (1195) ap Iorwerth (1155) ap Llywarch (1120) ap Bran of Anglesey, a man
cited in Dwnn ii 265 & 268.
Once we detach Adda from Iorwerth Drwyndwn on Bartrum's chart, we are left with his son, Llewelyn, as an only child. 
Bartrum's "Welsh Genealogies AD300-1400" on his chart "Gruffudd ap Cynan 4"
For our dating of Rhiryd Flaidd, see our paper on him at the following link:
There is no Welsh word "pothan". We suggest it is either a poor phonetic spelling of "Boddar" meaning "a nuisance or
pest" or of "boddran" meaning "to bother"
Vis Shropshire, 359 cites this Philip's mother as a daughter and heiress of Alexander Middleton of Shropshire. Thereafter,
that Middleton family was paternally descended from the Welshman, Philip ap Rhiryd ap Dafydd ap y Pothan Flaidd
Dictionary of Welsh Biography, page 417, asserts that Iorwerth Drwyndwn had but one son, Llywelyn.