Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
SEM images of vascular bundles from fracture surfaces. In the cross section, only the tracheids are visible in the mature endocarp (A) and have a polygonal cross section (B). From the former phloem cells, only fragments are left (arrows in (B)). In a longitudinally broken vascular bundle (C), scalariform thickenings of the tracheids are clearly visible (D). No pronounced perforation plates are visible at the ends of the tracheids (arrows in (D)).
