The omnipresent water fern Azolla caroliniana does not contain lignin

► Macrospores and microspores of Azolla caroliniana contain p-coumaric acid and ferulic acid-based sporopollenin. ► Contrary to common opinion, leaves and roots of A. caroliniana do not contain lignin. ► The polyphenolic component(s) of A. caroliniana resemble(s) that/those of higher plant condensed tannins.