Note that this scheme places Fraser fir in subsection Medianae and balsam fir in subsection Laterales; this separation is based on whether bract scales are exserted and the seed scales reniform (Medianae, Fraser fir), or bract scales are included and seed scales are cuneate-flabellate (Laterales, balsam fir) (Farjon and Rushforth 1989).