Here is my tentative translation of stanza 13.
(a) Craoibh fhuilme do fhâs
(b) ô n-Athlamhan Aodh
(c) sen nûa anonn a fhrémh
(d) ûa do C[h]unn an craoibh
A branch of a palm tree grew
from Aedh Athlamhan,
from the ancient up to the new, [he was] its root;
[Cormac] the grandson to Conn [was] the branch.