Structure and Development of the Lateral-Line Aerenchyma in Bracken Ferns (Pteridium: Dennstaedtiaceae)

Premise of research. Bracken ferns have a worldwide distribution. Plants consist of aerial fronds with petioles (stipes) that extend underground to specialized subterranean stems (rhizomes). A narrow continuous surface strip of specialized aerenchyma on each side of rhizomes and stipes, referred to as the lateral line, forms a pathway for gases. Developmental changes in the lateral line appear to affect gas exchange and influence water relations, soil exploitation, dormant survival, and disease resistance in these plants. An integrated account of the ontogeny and cytochemistry of the lateral line in the rhizomes and stipes of Pteridium has not been published.Methodology. LM with fluorescence cytochemistry, supported by SEM, was used to compare developmental changes in tissues of the lateral-line aerenchyma in the stipes (petioles) and rhizomes (stems) of representative bracken taxa.Pivotal results. The lateral lines of the rhizome and stipe in Pteridium aquilinum and Pteridium esculentum are a continuous ...