No relation to : Flaxes such as Cultivated Flax (Linum usitatissimum) [plants with similar names belonging to differing families].

Hybridizes with : Purple Toadflax, (Linaria purpurea) to produce Linaria × dominii which is fertile and is able to spread into localised gatherings, but requires the localised presence of the two parents.

Some similarities to : other Toadflaxes, but flowers larger than those of Purple Toadflax and smaller than those of Common Toadflax. The spur behind the flower is very short in comparison to that of Common Toadflax.

The flowers of toadflaxes are said to resemble a toads mouth, hence the name. because toadflaxes are mildly poisonous to livestock, these are regarded as toxic weeds. [However, your author has been un-successful at finding the identity of any poisonous substances within them apart from 'mildly poisonous glycosides']. In America Linaria species are invasive species.