Lab 7 -- Stems 2
These photos were taken from sections made by students in the second
lab
on stems, which looked at conifers, ferns, and other early vascular
plants.
Here are a few images of the fern (species to be determined) rachis
that was sectioned in lab. The U-shaped stele is in the center
and in the closer views you can see that it is amphiphloic like the
other ferns we studied. Notice also the thick walled
fibers inside the epidermis. There is also an endodermis around
the stele.
Another section through the stele...
Here is a closeup of the fibers at the edge of the rachis.
The remaining six images are from longitudinal sections of the
fern rachis. These views allowed us to see tracheid wall pitting
along with the walls of fibers out near the epidermis. Most of
the tracheids in these images have scalariform pits.
This one shows a narrow protoxylem tracheid with annular wall
thickenings.
The final two images are longitudinal sections. In the first of
the two, you can see how cell length is increasing going to the right
towards the thick-walled fibers.
This closer view shows the thick walls of the fibers near the epidermis
