Regarding Irish herbals: two interesting but obscure modern Irish sources are:
"Sean-Oideasai/ Leighis" in Be/aloideas 9, no.2. (an edition without
translation of a late 18th century county Cork compilation of herbal cures.
According to the editor, it draws on a good deal of probably oral
(folklore) material. (44 pages)
There are 18 pages of material on herbal cures in Aodh Mac Domhnaill's
(1802-1867) "Fealsu/nach" (edited in 1967 by Colm Beckett for An
Clo/chomhar, Dublin). The material probably derives from county Meath.
Also, N.J.A. Williams has an interesting article, Some Irish Plant Names,
(pp 449-462) in Sages, Saints and Storytellers (An Sagart, Maynooth, 1989).