Due to new genetic research, it has now been placed in the vastly expanded family Plantaginaceae.

The members of this genus are known in English as toadflax, a name shared with several other related genera.

The North American species do not appear to form interspecific hybrids at all.

The most common mode of reproduction is self-fertilization, with occasional fertilization by another plant of the same species.

[1] Closely related genera include the Linaria (Eurasian toadflaxes), Antirrhinum (snapdragons) and Cymbalaria (ivy-leaved toadflaxes).