The incipit of the antiphon Germinavit radix Jesse (Cantus ID 002941) quoted in C and T (opening of the passage "Germinavit radix Jesse.."):
1--d---ef---g---g----4
"Germinavit" (http://cantusindex.org/id/002941)
Medieval Christmas - Noël médiévaux: Tenth- to Sixteenth-Century secular & liturgical music for Feasts days, Orlando consort, Harmonia Mundi HMU 90 7418
The concordance in I-Mfd 1 is not part of a cycle, but it does contain the ascription.
The transcription in AMMM 13 contains an error in the last chord; it gives a d instead of a g in the contratenor bassus.