Hybridizes with: Argentine Fleabane to produce Erigeron bonariensis × canadensis.

Before the genus Conyza was entirely substituted by the genus Erigeron, Blue Fleabane (Erigeron acris) used to form a Erigeron X Conyza Inter-Genera hybrid with Canadian Fleabane called X Conyzigeron huelsenii, the genera of which (Conyzigeron) is a semantic amalgamation of Erigeron and Conyza. This so-called 'inter-genera' hybrid occurs only sporadically when the two parents are present nearby - in disturbed sandy places in Southern England. This hybrid is sterile and is intermediate in hairiness between the two species with pale-mauve ray-florets (which are not splayed out and hardly protrude from the phyllaries). BSBI distribution of X Conyzigeron huelsenii. But since the genus name change, this is no longer an impossible inter-genera hybrid. It is certainly still a hybrid though!

Not to be confused with: Canadian Goldenrod (Solidago canadensis) [a plant with similar name].

Like Daisy, Common Fleabane contains the poisonous polyacetylene Lachnophyllum Ester.

Most unusually, the yellow disc-florets in the centre have but four lobes and not the usual 5-lobes.