SEM studies on vessels in ferns. 9. Dicranopteris (Gleicheniaceae) and vessel patterns in leptosporangiate ferns.

Ferns in which vessels have been demonstrated to date are phylogenetically relatively specialized and characteristic of habitats with marked extremes in temperature and water availability. These specifications do not apply to the Gleicheniaceae, which indicates that vessels may occur in a range of more primitive ferns, including those from more nearly mesic habitats. Vessels in Dicranopteris have perforation plates (both lateral and terminal) with morphology similar to that of lateral wall pitting as seen with light microscopy. Scanning electron microscopy (SEM) is therefore necessary to demonstrate presence of perforations. Vessel presence in Dicranopteris is important in forming a picture of vessel presence and specialization in ferns, the phylogenetic and ecological distribution of which may differ from the patterns found in monocotyledons and dicotyledons. We believe that presence of vessels may not be a reliable indicator of phylogenetic position among ferns.