Ambelos grece vitis quamvis ampelos scribant nam quandocumque .p. littera .m. sequitur transit in sonum .b. ut infra in ampelos.
Ambelos is Greek for Latin vitis ("vine”}; although the Greeks always write ampelos, but whenever the letter "p” follows "m” it changes its pronunciation to /b/. Cf. also the entry Ampelos further down.
For more information see the Commentary section of B littera