Mode is not octave species. What secular mediæval songs use a reciting tone?

Cait Webb once pointed out on her blog that for many instrumentalists Mode I (later "dorian") just didn't fit, despite being by far the commonest one - the range of many instruments bottomed out at the tonic so the standard final cadential pattern, passing through the subtonic, was physically impossible. The result must have sounded to a contemporary ear as odd as Highland pipes trying to play a normal tonal melody.