The morphology of the tracheary elements of the climbing fern Salpichlaena (Blechnaceae) were analyzed by means of LM and SEM. Two preparative techniques were employed: maceration and sectioning. Under SEM macerated tracheary elements from roots, rhizomes and leaf rachises showed large scalariform perforations lacking pit membranes, thus constituting apparent perforation plates. The perforations showed terminal as well as lateral positions. “Multiple end-wall” and “intermittent” perforation plates were also observed. In sectioned material tracheary cells exhibited mostly intact pit membranes conforming tracheids with scalariform and circular to oval wall pitting. In roots, true perforations seemed to be present in some tracheary cells. A different degree of pit membrane perforations were registered in both macerated and sectioned material, thus suggesting the existence of “incipient vessel elements”. According to our observations macerations produce alterations in the xylem tissue, which can lead to misinterpretations.
incipient vessel elements