A gloss in the Old-Irish law-tract Uraicecht na Ríar states that the satire of glám dícenn takes place ‘under the shade of a whitethorn, without any thorns on it’. As this kind of tree always bears thorns, the contents of this gloss seem curious. The aim of this paper is therefore to discuss its possible meaning, through an analysis of evidence elsewhere for glám dícenn and other satires and invectives, and also by a brief examination of the status of whitethorn in early medieval Ireland.