Vessels in roots and rhizomes of Dryopteris crassirhizoma (Dryopteridaceae) from Heilongjiang province, China

In the present study, tracheary elements in roots and rhizomes of Dryopteri s crassirhizoma were observed with scanning electron microscopy (SEM). SEM observation revealed that all tracheary elements in both organs were vessel s. These vessel elements have end-wall perforation plates and lateral-wall perforation plates. End-wall perforation plates in roots are more specializ ed than in rhizomes; they are all scalariform and obliquely positioned in e nd walls. Most end-wall perforations, especially in the center portion of e nd-wall perforation plates, lack pit membrane remnants, but pit membrane re mnants are relatively abundant in some end-wall perforations of roots and r hizomes. It is noteworthy that several larger perforations on lateral walls usually are grouped together and form local lateral-wall perforation plate s. Wide perforations alternating with narrow perforations characterize vess els of roots and rhizomes, in addition, the majority of perforations in lat eral-walls have porose pit membranes or pit membrane remnants, range from i ntact pit membrane to nearly devoid of pit membrane remnants. Some vessels in rhizomes have several facets in which long scalariform pits have various degrees of porose membranes. These vessels contact several other tracheary elements for transferring materials.